A fight broke out in Hakkari province near the Iraqi border on Wednesday night after soldiers encountered a group of about 20 rebels, the sources said on condition of anonymity.

The army launched an operation in Hakkari this week after three soldiers on foot patrol were killed by a bomb. Thousands of soldiers are in the region, the sources said.

The PKK, based largely in northern Iraq, said in April 2009 that it would take no offensive action but has said in recent weeks it could resume attacks if it is targeted by the Turkish military.

The rebels have waged a 25-year armed campaign for autonomy in the mainly Kurdish southeast in a conflict that has claimed 40,000 lives.