diff --git a/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java b/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
index 6a35954322f8..f45f467071f5 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
@@ -15,11 +15,11 @@
  */
 package org.intellij.lang.regexp.psi;
 
-import com.intellij.psi.PsiNamedElement;
+import com.intellij.psi.PsiNameIdentifierOwner;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public interface RegExpGroup extends RegExpAtom, PsiNamedElement {
+public interface RegExpGroup extends RegExpAtom, PsiNameIdentifierOwner {
 
   boolean isCapturing();
 
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java b/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
index 7c2d6139c1a7..265d26a6aecd 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
@@ -26,6 +26,7 @@ import org.intellij.lang.regexp.psi.RegExpGroup;
 import org.intellij.lang.regexp.psi.RegExpPattern;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 public class RegExpGroupImpl extends RegExpElementImpl implements RegExpGroup {
   public RegExpGroupImpl(ASTNode astNode) {
@@ -98,6 +99,12 @@ public class RegExpGroupImpl extends RegExpElementImpl implements RegExpGroup {
     throw new AssertionError();
   }
 
+  @Override
+  public @Nullable PsiElement getNameIdentifier() {
+    final ASTNode nameNode = getNode().findChildByType(RegExpTT.NAME);
+    return nameNode == null ? null : nameNode.getPsi();
+  }
+
   public static boolean isPcreConditionalGroup(ASTNode node) {
     return node != null && node.findChildByType(RegExpTT.PCRE_CONDITIONS) != null;
   }
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/nonAsciiCharacters/RegexNamedGroupWithNonAscii.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/nonAsciiCharacters/RegexNamedGroupWithNonAscii.java
new file mode 100644
index 000000000000..e7682cc7bcd9
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/nonAsciiCharacters/RegexNamedGroupWithNonAscii.java
@@ -0,0 +1,29 @@
+class RegexTest {
+  void testRegexNamedGroups() {
+    // Non-ASCII characters in named group names should be highlighted
+    // language=regexp
+    String a = "(?<<error descr="Invalid group name"><warning descr="Non-ASCII characters">水</warning></error>>a)";
+    // language=regexp
+    String b = "(?<<error descr="Invalid group name">group_<warning descr="Non-ASCII characters">水</warning></error>>a)";
+    // language=regexp
+    String c = "(?<<error descr="Invalid group name"><warning descr="Non-ASCII characters">水</warning>_group</error>>a)";
+    // language=regexp
+    String d = "(?<<error descr="Invalid group name">my_<warning descr="Non-ASCII characters">группа</warning>_123</error>>a)";
+    
+    // Multiple named groups with non-ASCII
+    // language=regexp
+    String e = "(?<<error descr="Invalid group name"><warning descr="Non-ASCII characters">первая</warning></error>>a)(?<<error descr="Invalid group name"><warning descr="Non-ASCII characters">вторая</warning></error>>b)";
+    
+    // ASCII only group names should not be highlighted
+    // language=regexp
+    String f = "(?<group>a)";
+    // language=regexp
+    String g = "(?<<error descr="Invalid group name">my_group_123</error>>a)";
+    
+    // Non-ASCII in pattern body (not in group name) - these are not checked by this test
+    // language=regexp
+    String h = "(?<group>水)";
+    // language=regexp
+    String i = "水";
+  }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/NonAsciiCharactersTest.java b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/NonAsciiCharactersTest.java
index 4572d19cd915..24bf1bf871a9 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/NonAsciiCharactersTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/NonAsciiCharactersTest.java
@@ -128,4 +128,17 @@ public class NonAsciiCharactersTest extends DaemonAnalyzerTestCase {
     myInspection.CHECK_FOR_FILES_CONTAINING_BOM = false;
     doTest(".txt");
   }
+
+  public void testRegexNamedGroupWithNonAscii() throws Exception {
+    myInspection.CHECK_FOR_DIFFERENT_LANGUAGES_IN_ANY_OTHER_WORD = false;
+    myInspection.CHECK_FOR_DIFFERENT_LANGUAGES_IN_IDENTIFIER_NAME = false;
+    myInspection.CHECK_FOR_DIFFERENT_LANGUAGES_IN_COMMENTS = false;
+    myInspection.CHECK_FOR_DIFFERENT_LANGUAGES_IN_STRING = false;
+    myInspection.CHECK_FOR_NOT_ASCII_IN_ANY_OTHER_WORD = false;
+    myInspection.CHECK_FOR_NOT_ASCII_IDENTIFIER_NAME = true;
+    myInspection.CHECK_FOR_NOT_ASCII_COMMENT = false;
+    myInspection.CHECK_FOR_NOT_ASCII_STRING_LITERAL = false;
+    myInspection.CHECK_FOR_FILES_CONTAINING_BOM = false;
+    doTest(".java");
+  }
 }
diff --git a/platform/lang-impl/src/com/intellij/codeInspection/NonAsciiCharactersInspection.java b/platform/lang-impl/src/com/intellij/codeInspection/NonAsciiCharactersInspection.java
index cf7429babbfd..eb78fc52ccb8 100644
--- a/platform/lang-impl/src/com/intellij/codeInspection/NonAsciiCharactersInspection.java
+++ b/platform/lang-impl/src/com/intellij/codeInspection/NonAsciiCharactersInspection.java
@@ -25,6 +25,7 @@ import com.intellij.usages.ChunkExtractor;
 import org.jetbrains.annotations.*;
 
 import java.nio.charset.Charset;
+import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -203,7 +204,13 @@ public final class NonAsciiCharactersInspection extends LocalInspectionTool {
   }
 
   private static boolean isFileWorthIt(@NotNull PsiFile file) {
-    if (InjectedLanguageManager.getInstance(file.getProject()).isInjectedFragment(file)) return false;
+    if (InjectedLanguageManager.getInstance(file.getProject()).isInjectedFragment(file)) {
+      Language language = file.getLanguage();
+      language = Objects.requireNonNullElse(language.getBaseLanguage(), language);
+      if (!language.getID().equals("RegExp")) {
+        return false;
+      }
+    }
     VirtualFile virtualFile = file.getVirtualFile();
     if (virtualFile == null) return false;
     CharSequence text = file.getViewProvider().getContents();
diff --git a/python/src/com/jetbrains/python/codeInsight/PythonRegExpHost.java b/python/src/com/jetbrains/python/codeInsight/PythonRegExpHost.java
index 563c4a9baaae..15c9cbfe8033 100644
--- a/python/src/com/jetbrains/python/codeInsight/PythonRegExpHost.java
+++ b/python/src/com/jetbrains/python/codeInsight/PythonRegExpHost.java
@@ -3,11 +3,9 @@ package com.jetbrains.python.codeInsight;
 
 import com.intellij.lang.injection.InjectedLanguageManager;
 import com.intellij.psi.PsiLanguageInjectionHost;
+import com.jetbrains.python.PyNames;
 import com.jetbrains.python.psi.LanguageLevel;
-import org.intellij.lang.regexp.DefaultRegExpPropertiesProvider;
-import org.intellij.lang.regexp.RegExpLanguageHost;
-import org.intellij.lang.regexp.RegExpTT;
-import org.intellij.lang.regexp.UnicodeCharacterNames;
+import org.intellij.lang.regexp.*;
 import org.intellij.lang.regexp.psi.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -117,4 +115,30 @@ public final class PythonRegExpHost implements RegExpLanguageHost {
   public boolean isValidNamedCharacter(RegExpNamedCharacter namedCharacter) {
     return UnicodeCharacterNames.getCodePoint(namedCharacter.getName()) >= 0;
   }
+
+  @Override
+  public boolean isValidGroupName(String name, @NotNull RegExpGroup group) {
+    // non-ascii characters are allowed as group names in Python 3
+    // the specification is `<XID_Start> <XID_Continue>*`
+    int offset = 0;
+    int codePoint = name.codePointAt(offset);
+    
+    // First character must be XID_Start
+    if (!Character.isUnicodeIdentifierStart(codePoint)) {
+      return false;
+    }
+    
+    offset += Character.charCount(codePoint);
+    
+    // Remaining characters must be XID_Continue
+    while (offset < name.length()) {
+      codePoint = name.codePointAt(offset);
+      if (!Character.isUnicodeIdentifierPart(codePoint)) {
+        return false;
+      }
+      offset += Character.charCount(codePoint);
+    }
+    
+    return true;
+  }
 }
diff --git a/python/testSrc/com/jetbrains/python/PyRegexpTest.java b/python/testSrc/com/jetbrains/python/PyRegexpTest.java
index 12b9fbbbbb14..7ce2ec498537 100644
--- a/python/testSrc/com/jetbrains/python/PyRegexpTest.java
+++ b/python/testSrc/com/jetbrains/python/PyRegexpTest.java
@@ -289,6 +289,24 @@ public class PyRegexpTest extends PyTestCase {
     );
   }
 
+  @TestFor(issues="PY-35730")
+  public void testGroupNameIsValidIdentifier() {
+    //noinspection NonAsciiCharacters
+    testHighlighting(
+      """
+        import re
+        re.compile("(?P<水>水)")  # non-ascii is a valid group name, a warning will be reported by `NonAsciiCharactersInspection`
+        re.compile("(?P<𝕏>水)")  # ok character outside the BMP
+        
+        # broken case IJPL-217664
+        # re.compile("(?Perror descr="Invalid group name">😀</error>>水)")  # bad character outside the BMP
+        
+        re.compile("(?P<<error descr="Group name expected"> </error>a>水)")
+        re.compile("(?P<<error descr="Group name expected">0</error>a>水)")
+        re.compile("(?P<<error descr="Invalid group name">a$b</error>>水)")
+        """);
+  }
+
   @Nullable
   @Override
   protected LightProjectDescriptor getProjectDescriptor() {