Kurdish rebels killed 13 Turkish soldiers Sunday in a clash in the country's southeast, and troops shelled an area near the Iraqi border to try to stop the rebels from escaping across the border, AP quoted the military as saying. The soldiers were killed in the southeastern province of Sirnak, not far from where a rebel was killed earlier in the week, said a statement on the military's Web site. An operation to track down the rebels was under way, and troops shelled areas near the border to try to prevent rebels from reaching their bases in northern Iraq, the statement said.