Is it advisable to have non-ascii characters in the URL?

Question

We are currently working on a I18N project. I am wondering what are the complications of having the non-ascii characters in the URL. If its not advisable, what are the alternatives to deal with this problem?

EDIT (in response to Maxym's answer): The site is going to be local to specific country and I need not worry about the world wide public accessing this site. I understand that from usability point of view, It is really annoying. What are the other technical problem associated with this?

Answer 1

I would say no. The reason is simple -> if you rely on world wide public, then it would be a big problem for people to type your url. I live in "cyrillic" world, it is possible to create cyrillic urls, but no one succeed with that, because even we are pretty lazy to change language and get used to type latin...

Update:
I can't say about alternatives, but sometimes some languages have informal or formal letter substitute, e.g. in German you can write Ö but in url you could see OE instead. Also you can consider english words, or words with similar sounds (so people from your country can remeber that writing, and other "countries" won't harm