The PKK, listed as a terrorist group by Turkey and many of its Western allies, has waged an armed campaign for self-rule in the Kurdish-majority east and southeast since 1984.

The conflict has claimed more than 37,000 lives, but the group's attacks in the past 10 years have usually targeted security forces rather than civilians.

The Turkish army killed four PKK members in Bingol and the southeastern province of Hakkari while two Kurdish fighters and two soldiers were killed the previous night in fighting, security  sources said.

The Turkish military has stepped up action against the PKK since December, conducting air raids and a week-long ground offensive against PKK bases in northern Iraq.