diff --git a/tools/gulp/tasks/validate-release.ts b/tools/gulp/tasks/validate-release.ts
index 36ec8ef6aaac..ba7deb6ecf09 100644
--- a/tools/gulp/tasks/validate-release.ts
+++ b/tools/gulp/tasks/validate-release.ts
@@ -6,7 +6,10 @@ import {green, red} from 'chalk';
 import {sequenceTask} from '../util/task_helpers';
 
 /** RegExp that matches Angular component inline styles that contain a sourcemap reference. */
-const inlineStylesSourcemapRegex = /styles: ?\[(?:"|').*sourceMappingURL=.*(?:"|')/;
+const inlineStylesSourcemapRegex = /styles: ?\[["'].*sourceMappingURL=.*["']/;
+
+/** RegExp that matches Angular component metadata properties that refer to external resources. */
+const externalReferencesRegex = /(templateUrl|styleUrls): *["'[]/;
 
 task('validate-release', sequenceTask(':publish:build-releases', 'validate-release:check-bundles'));
 
@@ -38,5 +41,9 @@ function checkPackageBundle(bundlePath: string): string[] {
     failures.push('Bundles contain sourcemap references in component styles.');
   }
 
+  if (externalReferencesRegex.exec(bundleContent) !== null) {
+    failures.push('Bundles are including references to external resources (templates or styles)');
+  }
+
   return failures;
 }