Fit regions in least possible fixed-size rectangles?

Hi,

I'm looking for a fast algorithm solving a problem, even though I've been reading quite some research papers I can't find a suitable solution. Someone a good idea / reference to literature?

Suppose you have a 2D map containing rectangles (regions) (possibly overlapping). Also, given is a fixed size rectangle (container). How can I find a way to contain all regions in as little containers as possible? Some notes:

- Container may be rotated in 90 degree steps
- Every region must be COMPLETELY covered in at least one container

Anyone an idea? Efficiency is quite important since over 25000 regions are to be expected.

Thanks a million,

Cees