REGULAR EXPRESSION POSSIBLE PROBLEM

Hi PG team ,
my database is in UNICODE
I try this (with Bulgarian chars):

SELECT 'Тест проба' ~* 'тест' as result

returns FALSE

above query is same as:

SELECT 'Test exam' ~* 'test' as result

retuns TRUE

the only different is that strings are in English

Is there problem with cyrilic?
I tested postgresql server 8.0.0beta-4 in Win32 platform, but I have same
problem in linux/postgresql 7.4.x with UNICODE database.

Thanks in advanced.

regards Antony Raijekov