Clean out illegal characters i URL - Wordpress plugin

I need a simple plugin that can solve the following problem. We have a lot of older installations of WordPress, and in these installations, it has been possible to build a URL with illegal characters in. It is especially Danish letters that gives us problems. We will need a plugin that can run through all the addresses and updated them so that the illegal character disappears. Or rename them acording to the way Wordpress do it. A URL example. look like [login to view URL]øbenhavn/ or [login to view URL] C3% B8benhavn/ In short, this plugin must be installed and then clean up all URLs in both posts, pages, tags, etc. Afther that all URL are without illegal characters. The rules for this cleanup is the way Wordpress handels illegal characters. And if i find a good supplier for this, then i have other tasks to be done.