See also: Unicode and Character Encodings in Perl.

I have tried it in few languages , but \W removes all characters that are not english.
Don't know what it's problem. Here is my code:
Url russian(with russian characters in url):domain.com/ru/search/игра
perl code :$params{$_} =~ s/[\W]//g for keys %params;
another try with encode-decode:

use Encode qw(encode decode);
$params{search_in_page}=decode('utf-8',$params{search_in_page});
$params{$_} =~ s/[\W]//g for keys %params;
$params{search_in_page}=encode('utf-8',$params{search_in_page});
[download]

what can be the problem ?

what can be the problem ?

The problem is most likely that your data isn't what you think it is.

Try the following script:

use strict;
use warnings;
binmode STDOUT, ':encoding(UTF-8)';
use Encode qw/decode_utf8/;
while (<>) {
    $_ = decode_utf8 $_;
    s/\W//g;
    print;
}
[download]

Some in- and output:

möp spaß     # input
möpspaß      # output
АБВГ-ДЕЖ/ЗDD # input
АБВГДЕЖЗDD   # output

So it preserves both German umlauts and Cyrillic characters.

Please actually read the article I gave you a link to, it contains advice on how to debug such problems.

Perl 6 - second systems done right

Then you need to get far more specific in what you want to remove, and also why.

Great, then what should it remove, what are the dangerous chars?

Let's say I need regex to get rid of all NOT letters of all languages that utf-8 support.