The clashes occurred in a mountainous area in the province of Sirnak, near the border with Iraq, as part of a continuing operation against the Kurdistan Workers' Party (PKK), the sources said.

The PKK, listed as a terrorist group by Ankara and much of the international community, has stepped up its attacks this year in its fight for self-rule in Turkey's mainly Kurdish east and southeast.

The army has launched a large-scale crackdown against the group in these areas and amassed troops on the border with Iraq, where the militants take refuge.

Army chief General Yasar Buyukanit insisted Wednesday on the need for a military incursion into Kurdish-run northern Iraq to crack down on PKK bases there, but said he needed the government's green light to do so.

Turkey also accuses Iraqi Kurds of tolerating and even supporting the PKK.

The government has not ruled out an incursion into Iraq, but has said it will focus on fighting the PKK inside Turkey and seek dialogue with Baghdad to resolve the problem of the safe haven the rebels enjoy in the north.

More than 37,000 people have died since 1984 when the PKK took up arms.