uri routing - doesn't work with colon ( : )

[eluser]tewoos[/eluser]
I have a problem with this expression:
$route['tutorial\d+)(/(.*))?'] = "tutorial";

it gives an 403 Forbidden error. an example for the usage of this url is like below:
www.site.com/tutorial:1200/title-of-tutorial-with-id-1200

if I try this expression with a '-' instead of ':' after tutorial string, it works perfectly. how can I use : (colon) in urls ?

in config.php allowed characters is set like below:
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_-';