$config['permitted_uri_chars'] doesn't work properly

[eluser]asim111[/eluser]
I just installed Codeigniter 2.1.0

I want to allow just few characters in URLs. By default only these are allowed: a-z 0-9~%.:_-

I'm having some problems with $config['permitted_uri_chars'] as it is not working properly for me for some reasons.

I used few characters in URL for testing purposes such as single quote, double quote, £ pound sign. I can't see any restriction on these characters or there is NO ERROR message like

"The URI you submitted has disallowed characters."

My test URL was:

Code:

http://localhost/codeigniter/index.php/welcome/index/abc£1/

And on the other hand, I tried percentage sign % which is allowed in URLs and got the following error message

Code:

400 Bad Request: Your browser sent a request that this server could not understand.

Am i doing something wrong? please help
Thanks