Two village guards -- government-armed Kurdish militia supporting the Turkish army against the outlawed Kurdistan Workers' Party (PKK) -- were also killed in the clash near the town of Mutki in Bitlis province, the source added.

The latest deaths brought to 18 the number of PKK rebels killed in Bitlis in two days and increased Turkish losses to five village guards.

The PKK, listed as a terrorist organisation by Ankara and much of the international community, has been fighting for Kurdish self-rule in Turkey's mainly Kurdish east and southeast since 1984. The conflict has claimed more than 37,000 lives.

The Turkish army has stepped up its crackdown against the group since December, intensifying operations in the southeast and conducting air raids on PKK camps in neighbouring northern Iraq, where the rebels take refuge.

Ankara blames the PKK and a group of militants affiliated to the rebels for a recent string of bomb attacks in urban centres, including two bomb attacks in Istanbul on July 27 which killed 17 people and wounded more than 150.