detect cyrillic letters in string (Regexp)

//detect cyrillic letters in string (Regexp)

        //cyrillic letters
        public static bool ContainsRus(string TestString)
        {
            return
                Regex.IsMatch(TestString, @"[а-я]", RegexOptions.IgnoreCase);
        }

        //cyrillic letters and spaces
        public static bool ContainsRusOrSpace(string TestString)
        {
            return
                Regex.IsMatch(TestString, @"[а-я]|\s", RegexOptions.IgnoreCase);
        }