Hmm ok, I thought it was shot in Tunisia only because Ewan McGregor makes mention of it in his documentary "Long Way Down" with Charley Boorman as they motorcycled from Scotland down to Sth Africa and they make a stop over on the way down, here's an exerpt if you fast forward to about 6 minutes into the video:
http://www.youtube.com/watch?v=dmIQdTHD3rA
Edit: oops I read just Algeria but article says Tunisian border...