diff --git a/src/main/java/eu/europa/ted/eforms/sdk/analysis/domain/schematron/SchematronAssert.java b/src/main/java/eu/europa/ted/eforms/sdk/analysis/domain/schematron/SchematronAssert.java
index f2b541d..1c8edd5 100644
--- a/src/main/java/eu/europa/ted/eforms/sdk/analysis/domain/schematron/SchematronAssert.java
+++ b/src/main/java/eu/europa/ted/eforms/sdk/analysis/domain/schematron/SchematronAssert.java
@@ -2,16 +2,22 @@
 
 public class SchematronAssert {
   private final String id;
+  private final String patternId;
   private String diagnostics;
 
-  public SchematronAssert(String id) {
+  public SchematronAssert(String id, String patternId) {
     this.id = id;
+    this.patternId = patternId;
   }
 
   public String getId() {
     return id;
   }
 
+  public String getPatternId() {
+    return patternId;
+  }
+
   public String getDiagnostics() {
     return diagnostics;
   }
diff --git a/src/main/java/eu/europa/ted/eforms/sdk/analysis/fact/SchematronFileFact.java b/src/main/java/eu/europa/ted/eforms/sdk/analysis/fact/SchematronFileFact.java
index 97140a7..4758d2a 100644
--- a/src/main/java/eu/europa/ted/eforms/sdk/analysis/fact/SchematronFileFact.java
+++ b/src/main/java/eu/europa/ted/eforms/sdk/analysis/fact/SchematronFileFact.java
@@ -1,7 +1,9 @@
 package eu.europa.ted.eforms.sdk.analysis.fact;
 
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -40,9 +42,32 @@ public List<SchematronPattern> getPatterns() {
     return schematronFile.getPatterns();
   }
 
+  /**
+   * Return the list of assert identifiers that appear more than once in the same phase.
+   * 
+   * @return list of duplicate assert ids
+   */
   public List<String> getDuplicateAssertIds() {
-    Set<String> set = new HashSet<String>();
-    return getAsserts().stream().map(SchematronAssert::getId).filter(id -> !set.add(id))
+    // Mpa from the pattern id to the id of the phase it is part of
+    Map<String, String> patternToPhase = new HashMap<>();
+    getPhases().forEach(phase -> {
+      phase.getActivePatterns()
+          .forEach(patternId -> {
+            patternToPhase.put(patternId, phase.getId());
+          });
+    });
+
+    // Map from phase id to the set of assert ids it contains.
+    Map<String, Set<String>> phaseToAssertIds = new HashMap<String, Set<String>>();
+    return getAsserts().stream()
+        .filter(assrt -> {
+          String phaseId = patternToPhase.get(assrt.getPatternId());
+          Set<String> asserts = 
+              phaseToAssertIds.computeIfAbsent(phaseId, k -> new HashSet<String>());
+          // Keep SchematronAssert if its is already present in the same phase
+          return !asserts.add(assrt.getId());
+        })
+        .map(SchematronAssert::getId)
         .collect(Collectors.toList());
   }
 
diff --git a/src/main/java/eu/europa/ted/eforms/sdk/analysis/util/SchematronParser.java b/src/main/java/eu/europa/ted/eforms/sdk/analysis/util/SchematronParser.java
index 1a2cbf9..ccc7dbd 100644
--- a/src/main/java/eu/europa/ted/eforms/sdk/analysis/util/SchematronParser.java
+++ b/src/main/java/eu/europa/ted/eforms/sdk/analysis/util/SchematronParser.java
@@ -96,30 +96,44 @@ public static SchematronFile loadSchematronFile(Path schematronFilePath) {
     }
     
     // Parse all patterns
-    List<SchematronPattern> patterns = allChildren.stream()
+    List<SchematronPattern> patterns = new ArrayList<>();
+    List<SchematronAssert> asserts = new ArrayList<>();
+    allChildren.stream()
         .filter(node -> node.isElement() && "pattern".equals(node.getNodeName()))
-        .map(n -> ((IMicroElement)n).getAttributeValue("id"))
-        .map(s -> new SchematronPattern(s))
-        .collect(Collectors.toList());
+        .forEach(patternNode -> {
+          String patternId = ((IMicroElement)patternNode).getAttributeValue("id");
+          SchematronPattern pattern  = new SchematronPattern(patternId);
+          patterns.add(pattern);
+          asserts.addAll(parseAsserts(patternId, patternNode));
+        });
 
     schematronFile.setPatterns(patterns);
+    schematronFile.setAsserts(asserts);
 
-    // Parse all asserts
+    return schematronFile;
+  }
+
+  private static List<SchematronAssert> parseAsserts(String patternId, IMicroNode patternNode) {
     List<SchematronAssert> asserts = new ArrayList<>();
-    allChildren.stream()
+
+    List<IMicroNode> children = patternNode.getAllChildrenRecursive();
+    if (children == null) {
+      logger.error("Schematron file has unexpected structure in pattern", patternId);
+      // return an empty list, so that the prasing can continue
+      return asserts;
+    }
+
+    children.stream()
         .filter(node -> node.isElement() && "assert".equals(node.getNodeName()))
         .forEach(n -> {
           IMicroElement element = (IMicroElement)n;
-          String id = element.getAttributeValue("id");
-          SchematronAssert schematronAssert = new SchematronAssert(id);
+          String assertId = element.getAttributeValue("id");
+          SchematronAssert schematronAssert = new SchematronAssert(assertId, patternId);
           String diag = element.getAttributeValue("diagnostics");
           schematronAssert.setDiagnostics(diag);
           asserts.add(schematronAssert);
         });
-
-    schematronFile.setAsserts(asserts);
-
-    return schematronFile;
+    return asserts;
   }
 
   private static void handleError(IError error, Path schematronFilePath) {
diff --git a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1a.sch b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1a.sch
index 9ab9877..9903232 100644
--- a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1a.sch
+++ b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1a.sch
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <pattern id="EFORMS-validation-stage-1a" xmlns="http://purl.oclc.org/dsdl/schematron">
 	<rule context="/*">
-		<assert id="P-0001" role="ERROR" test="count(ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/efext:EformsExtension/efac:NoticeSubType/cbc:SubTypeCode) &gt; 0">
+		<assert id="DUPLICATE" role="ERROR" test="count(ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/efext:EformsExtension/efac:NoticeSubType/cbc:SubTypeCode) &gt; 0">
 			rule|text|P-0001
 		</assert>
 		<assert id="P-0002" role="ERROR" test="($noticeSubType = ('1', '2', '3', 'X01', 'X02') and count(cac:ProcurementProjectLot) = 0) or (not(cbc:NoticeTypeCode/text() = ('1', '2', '3', 'X01', 'X02')) and count(cac:ProcurementProjectLot) > 0)">
diff --git a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-1.sch b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-1.sch
index ead1ae9..7eb22e6 100644
--- a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-1.sch
+++ b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-1.sch
@@ -2,7 +2,7 @@
 <!--File generated from metadata database-->
 <pattern id="EFORMS-validation-stage-1b-1" xmlns="http://purl.oclc.org/dsdl/schematron">
 	<rule context="/*[$noticeSubType = '1']">
-		<assert id="ND-BusinessParty-1" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-1</assert>
+		<assert id="R-123-ABC" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-1</assert>
 		<assert id="ND-ContractingParty-1" role="ERROR" diagnostics="ND-ContractingParty" test="count(cac:ContractingParty) &gt; 0">rule|text|ND-ContractingParty-1</assert>
 		<assert id="ND-GazetteReference-1" role="ERROR" diagnostics="ND-GazetteReference" test="count(cac:AdditionalDocumentReference) = 0">rule|text|ND-GazetteReference-1</assert>
 		<assert id="ND-OperationType-1" role="ERROR" diagnostics="ND-OperationType" test="count(efac:NoticePurpose) = 0">rule|text|ND-OperationType-1</assert>
@@ -13,7 +13,7 @@
 		<assert id="ND-SenderContact-1" role="ERROR" diagnostics="ND-SenderContact" test="count(cac:SenderParty/cac:Contact) = 0">rule|text|ND-SenderContact-1</assert>
 	</rule>
 	<rule context="/*/cac:ContractingParty[$noticeSubType = '1']">
-		<assert id="BAD" role="ERROR" diagnostics="ND-Buyer" test="count(cac:Party) &gt; 0">rule|text|ND-Buyer-1</assert>
+		<assert id="ND-Buyer-1" role="ERROR" diagnostics="ND-Buyer" test="count(cac:Party) &gt; 0">rule|text|ND-Buyer-1</assert>
 	</rule>
 	<rule context="/*/cac:ProcurementProject[$noticeSubType = '1']">
 		<assert id="ND-ProcedureValueEstimate-1" role="ERROR" diagnostics="ND-ProcedureValueEstimate" test="count(cac:RequestedTenderTotal) = 0">rule|text|ND-ProcedureValueEstimate-1</assert>
diff --git a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-16.sch b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-16.sch
index 6d8e46d..55a1cca 100644
--- a/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-16.sch
+++ b/src/test/resources/eforms-sdk-tests/tedefo-2684/invalid/schematrons/dynamic/validation-stage-1b-16.sch
@@ -2,8 +2,8 @@
 <!--File generated from metadata database-->
 <pattern id="EFORMS-validation-stage-1b-16" xmlns="http://purl.oclc.org/dsdl/schematron">
 	<rule context="/*[$noticeSubType = '16']">
-		<assert id="ND-BusinessParty-16" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-16</assert>
-		<assert id="ND-ContractingParty-16" role="ERROR" diagnostics="ND-ContractingParty" test="count(cac:ContractingParty) &gt; 0">rule|text|ND-ContractingParty-16</assert>
+		<assert id="R-123-ABC" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-16</assert>
+		<assert id="DUPLICATE" role="ERROR" diagnostics="ND-ContractingParty" test="count(cac:ContractingParty) &gt; 0">rule|text|ND-ContractingParty-16</assert>
 		<assert id="ND-GazetteReference-16" role="ERROR" diagnostics="ND-GazetteReference" test="count(cac:AdditionalDocumentReference) = 0">rule|text|ND-GazetteReference-16</assert>
 		<assert id="ND-OperationType-16" role="ERROR" diagnostics="ND-OperationType" test="count(efac:NoticePurpose) = 0">rule|text|ND-OperationType-16</assert>
 		<assert id="ND-Part-16" role="ERROR" diagnostics="ND-Part" test="count(cac:ProcurementProjectLot[cbc:ID/@schemeName='Part']) = 0">rule|text|ND-Part-16</assert>
@@ -19,7 +19,7 @@
 	<rule context="/*/cac:ProcurementProjectLot[cbc:ID/@schemeName='Lot'][$noticeSubType = '16']">
 		<assert id="ND-LotProcurementScope-16" role="ERROR" diagnostics="ND-LotProcurementScope" test="count(cac:ProcurementProject) &gt; 0">rule|text|ND-LotProcurementScope-16</assert>
 		<assert id="ND-LotTenderingProcess-16" role="ERROR" diagnostics="ND-LotTenderingProcess" test="count(cac:TenderingProcess) &gt; 0">rule|text|ND-LotTenderingProcess-16</assert>
-		<assert id="ND-LotTenderingTerms-16" role="ERROR" diagnostics="ND-LotTenderingTerms" test="count(cac:TenderingTerms) &gt; 0">rule|text|ND-LotTenderingTerms-16</assert>
+		<assert id="BAD" role="ERROR" diagnostics="ND-LotTenderingTerms" test="count(cac:TenderingTerms) &gt; 0">rule|text|ND-LotTenderingTerms-16</assert>
 	</rule>
 	<rule context="/*/cac:ProcurementProjectLot[cbc:ID/@schemeName='Lot']/cac:TenderingProcess[$noticeSubType = '16']">
 		<assert id="BAD" role="ERROR" diagnostics="ND-AuctionTerms" test="count(cac:AuctionTerms) &gt; 0">rule|text|ND-AuctionTerms-16</assert>
diff --git a/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-1.sch b/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-1.sch
index e51be47..7eb22e6 100644
--- a/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-1.sch
+++ b/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-1.sch
@@ -2,7 +2,7 @@
 <!--File generated from metadata database-->
 <pattern id="EFORMS-validation-stage-1b-1" xmlns="http://purl.oclc.org/dsdl/schematron">
 	<rule context="/*[$noticeSubType = '1']">
-		<assert id="ND-BusinessParty-1" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-1</assert>
+		<assert id="R-123-ABC" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-1</assert>
 		<assert id="ND-ContractingParty-1" role="ERROR" diagnostics="ND-ContractingParty" test="count(cac:ContractingParty) &gt; 0">rule|text|ND-ContractingParty-1</assert>
 		<assert id="ND-GazetteReference-1" role="ERROR" diagnostics="ND-GazetteReference" test="count(cac:AdditionalDocumentReference) = 0">rule|text|ND-GazetteReference-1</assert>
 		<assert id="ND-OperationType-1" role="ERROR" diagnostics="ND-OperationType" test="count(efac:NoticePurpose) = 0">rule|text|ND-OperationType-1</assert>
diff --git a/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-16.sch b/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-16.sch
index 67d8951..fe2bc5c 100644
--- a/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-16.sch
+++ b/src/test/resources/eforms-sdk-tests/tedefo-2684/valid/schematrons/dynamic/validation-stage-1b-16.sch
@@ -2,7 +2,7 @@
 <!--File generated from metadata database-->
 <pattern id="EFORMS-validation-stage-1b-16" xmlns="http://purl.oclc.org/dsdl/schematron">
 	<rule context="/*[$noticeSubType = '16']">
-		<assert id="ND-BusinessParty-16" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-16</assert>
+		<assert id="R-123-ABC" role="ERROR" diagnostics="ND-BusinessParty" test="count(cac:BusinessParty) = 0">rule|text|ND-BusinessParty-16</assert>
 		<assert id="ND-ContractingParty-16" role="ERROR" diagnostics="ND-ContractingParty" test="count(cac:ContractingParty) &gt; 0">rule|text|ND-ContractingParty-16</assert>
 		<assert id="ND-GazetteReference-16" role="ERROR" diagnostics="ND-GazetteReference" test="count(cac:AdditionalDocumentReference) = 0">rule|text|ND-GazetteReference-16</assert>
 		<assert id="ND-OperationType-16" role="ERROR" diagnostics="ND-OperationType" test="count(efac:NoticePurpose) = 0">rule|text|ND-OperationType-16</assert>
diff --git a/src/test/resources/eu/europa/ted/eforms/sdk/analysis/cucumber/tedefo-2684.feature b/src/test/resources/eu/europa/ted/eforms/sdk/analysis/cucumber/tedefo-2684.feature
index 4f9aa4f..945979b 100644
--- a/src/test/resources/eu/europa/ted/eforms/sdk/analysis/cucumber/tedefo-2684.feature
+++ b/src/test/resources/eu/europa/ted/eforms/sdk/analysis/cucumber/tedefo-2684.feature
@@ -19,7 +19,7 @@ Feature: Schematron files - Assert id validation
     When I load all schematron files
     And I execute validation
     Then Rule "<expected rule>" should have been fired
-    And I should get 2 SDK validation errors
+    And I should get 3 SDK validation errors
 
     Examples:
      | expected rule                      |