The incident occurred before dawn in a mountainous area near Lice in the province of Diyarbakir.

The soldiers were returning from a security operation against separatist Kurdish rebels active in the region when they came under fire by a group of six people, the sources said.

Two civilians were killed and another wounded in the ensuing shootout, they said.

The authorities were looking into the possibility that the assailants might have been drug traffickers after a cannabis field was discovered near the site of the shooting.

Lice is known as a major centre of cannabis growing, which is illegal in Turkey.

On Monday, Turkish soldiers shot dead two villagers in a forest in the southern Hatay province, mistaking them for militants of the separatist Kurdistan Workers's Party (PKK), which has significantly stepped up violence in recent weeks.

The PKK, listed as a terrorist group by Ankara and much of the international community, took up arms for Kurdish self-rule in the southeast in 1984, sparking a conflict that has claimed some 45,000 lives.