Language-specific characters with the RegularExpressionValidator

Hello everybody,
I am using a RegularExpressionValidator to check if a field contains valid letters: [A-Z0-9_] or simply \w. The problem is that the page is international and if a person uses some language-specific letters like ó or æ it does not accept them. I have read that there are some 'flags' in regexp that can be set to accept language specific letters but I can not find how to do it in the validator.
Of course I could simply add those letters into the validation  [óæA-Z0-9_] or  [óæ\w] but this is not a very good solution - when I add another language, I have to go to all the places where are the RegularExpressionValidators and change their expressions :/ I am looking for a generic solution ...

Any explanation is appreciated :)

Thanks in advance,
Jozef A. Habdank

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