codeigniter 1.7 Disallowed Key Characters cyrillic character - codeigniter

Question

I have massage "Disallowed Key Characters" whit url like this:
/project/category/Португалски
if url containd only latin chars problem is gone.
Problem come after removing index.php.
For removing i use in
config.php :
$config['index_page'] = "";
and
.htacces
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php?$1 [L]
After this url's work fine exept this url's whit cyrillic chars.
I read many questions for this before me and try differend solutions like:
in core/input/ _clean_input_keys function i change
if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
to
if ( !preg_match("/^[a-z0-9а-яА-Я~%:_\/-]+$/i", $str))
i tried other variant of this expresion but result is the same.
in config.php i change:
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_-';
to
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-а-яА-Я';
after this i tried
$config['permitted_uri_chars'] = 'a-zA-Z\p{Cyrillic}0-9~%.:_\-';
result sill is same. Massage "Disallowed Key Characters".
When i remove .htaccess rile and put again index.php in config all work whit cyrillic without problem.
SOLVED -
I just change text in.htaccess file to:
RewriteEngine on
RewriteCond $1 !^(index\.php|images|robots\.txt)
RewriteRule ^(.*)$ /index.php/$1 [L]
Now evriting is work fine :)