diff --git a/ets2panda/ir/expressions/memberExpression.cpp b/ets2panda/ir/expressions/memberExpression.cpp
index 9bd788ce380e17b04d77aaabf94dca4f03ff28bf..7b9ad9fb97381417223c6e853f316394a91c835e 100644
--- a/ets2panda/ir/expressions/memberExpression.cpp
+++ b/ets2panda/ir/expressions/memberExpression.cpp
@@ -336,6 +336,12 @@ checker::Type *MemberExpression::AdjustType(checker::ETSChecker *checker, checke
         return TsType();
     }
     SetTsType(type == nullptr ? checker->GlobalTypeError() : type);
+    if (objType->IsETSUnionType() && type != nullptr && type->IsETSMethodType() && !type->IsETSArrowType()) {
+        if (!Parent()->IsCallExpression()) {
+            checker->LogError(diagnostic::UNION_MEMBER_METHOD_REFERENCE, {}, Start());
+            SetTsType(checker->GlobalTypeError());
+        }
+    }
     return TsType();
 }
 
diff --git a/ets2panda/test/ast/parser/ets/unionMemberReference.ets b/ets2panda/test/ast/parser/ets/unionMemberReference.ets
new file mode 100644
index 0000000000000000000000000000000000000000..2f9e9716af3bb4fb3b3f263e6814a3dad72b2689
--- /dev/null
+++ b/ets2panda/test/ast/parser/ets/unionMemberReference.ets
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+interface AType {
+    f(): void;
+}
+
+interface BType {
+    f(): void;
+}
+
+declare const x: AType | BType;
+
+(x as AType | BType).f;
+
+/* @@? 26:1 Error TypeError: Union member method reference is not supported and cannot be treated as a callable method */
\ No newline at end of file
diff --git a/ets2panda/util/diagnostic/semantic.yaml b/ets2panda/util/diagnostic/semantic.yaml
index bb8e6f39eca5bff4e51557d8cd44aa3786da5065..39be3ed1b18d7ffac0244a4749c0d798dae869a0 100644
--- a/ets2panda/util/diagnostic/semantic.yaml
+++ b/ets2panda/util/diagnostic/semantic.yaml
@@ -1417,6 +1417,10 @@ semantic:
   id: 245
   message: "Type {} is illegal in union member expression."
 
+- name: UNION_MEMBER_METHOD_REFERENCE
+  id: 186623
+  message: "Union member method reference is not supported and cannot be treated as a callable method"
+
 - name: UNION_NONCONSTRUCTIBLE
   id: 300
   message: "The union type is not constructible."