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, Anatolia news agency reported.

In another incident nearby 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.

The PKK, listed as a terrorist organisation by Ankara and much of the international community, has notably stepped up attacks this year.

The army has launched a large-scale crackdown against the group 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.