Sri Lankan troops have surrounded dozens of Tamil Tiger separatist rebels during fierce fighting in the island's north in a drive to end a 25-year civil war, the military said Thursday. The rebels - who once commanded a de facto state across a large swath of the island's north and east - have been pushed into a small sliver of coastal land measuring just 21 square kilometers, on the northeast coast. In the latest fighting, the military said government troops had surrounded a group of rebels in an area less than 1 square kilometer. A statement on the Defense Ministry's Web site also said its forces had cut a supply route to the rebels in the Puthkkudiyirippu area. It said the bodies of 13 rebels had also been recovered. Accounts of the battles cannot be verified because independent journalists are barred from the war zone.