User account names

We've recently had a lot of spam arriving, mostly written in an arabic script.

I can instaban users, and do so, but one of the junk accounts has been created with a login id that gives us a url that answers can't cope with, so I can't get to the users profile to click instaban...

Can we block the creation of names with such odd characters? (I don't mean the arabic script, that's fine IMHO, just whatever characters are causing the break)