One of the soldiers and the two rebels, members of the separatist Kurdistan Workers' Party (PKK), were killed in a clash in the Cudi mountains in Sirnak province, which borders Iraq and Syria, the sources said.

The second soldier died in the same area when he stepped on a landmine planted by suspected PKK militants.

Clashes between the army and the PKK in the countryside have significantly escalated this year and Kurdish militants have claimed a series of bomb attacks in urban centers.

The army has amassed troops in the southeast to step up security operations and stop what it says are increasing rebel infiltrations from neighboring northern Iraq, where the PKK found refuge after declaring a unilateral ceasefire in 1999. The truce was called off in June 2004.

The Kurdish conflict has claimed more than 37,000 lives since 1984 when the PKK, blacklisted as a terrorist group by Turkey, the European Union and the United States, took up arms for Kurdish self-rule in the southeast.