%20 need to replace with -

Dear All,
My website is being hit by some urls that is not
served
properly by nginx due to some characters like %20.

http://www.abc.com?param=test (Works fine)

http://www.abc.com?param=test%20again (Do no work)
it should be something like this http://www.abc.com?param=test-again

I want to replace %20 with - (Dash). Please suggest me best regex for
the
same.

Thanks,
Om

Posted at Nginx Forum:
http://forum.nginx.org/read.php?2,258629,258629#msg-258629