The clashes broke out Wednesday afternoon in a mountainous area in the province of Tunceli after the soldiers came under fire from militants of the separatist Kurdistan Workers' Party (PKK), the Tunceli governor's office said.

The security operation in the area was continuing, backed by air cover.

In another incident in Tunceli late Wednesday, PKK militants detonated a remote-controlled landmine on a road as a group of soldiers was passing, leaving five troops injured, one of them seriously, security sources said.

Two other landmine explosions Thursday blamed on the PKK left another soldier and a forestry worker injured in the southeastern province of Sirnak, officials said.

Landmine attacks have become a hallmark of PKK violence as the group, listed as a terrorist organisation by Ankara and much of the international community, stepped up attacks this year.

The army has launched a large-scale crackdown against the PKK in the east and southeast of the country and amassed troops on the border with Iraq, where the militants take refuge.

The PKK took up arms for self-rule in the Kurdish-majority region in 1984. The conflict has claimed more than 37,000 lives.