The army has been carrying out operations in the region near the Iraqi border, across which Kurdish groups often move to launch attacks on the Turkish military.

The PKK has stepped up attacks on the armed forces in southeast Turkey after ending a 14-month ceasefire at the start of June.

Scores of deaths

More than 80 soldiers have been killed so far this year, already exceeding the death toll in 2009.

In depth

 Turkey's cycle of violence  Profile: Kurdistan Workers Party

Last week, an attack near the Iraqi border left 12 soldiers and five rebels dead, while an attack in Istabul last month saw five soldiers and a teenager killed in a bomb attack in Istanbul.

Over the weekend, rebels were blamed for bombing a pipeline carrying oil from Iraq to Turkey, but there has been no claim of responsibility.

Violence surged after Abdullah Ocalan, the jailed PKK leader, said through his lawyers in May that he was abandoning efforts to seek dialogue with Ankara for a peaceful end to the 26-year conflict.

The mounting clashes have dealt a blow to a government initiative announced last year to boost Kurdish freedoms and investment in the impoverished southeast, in a bid to urge the PKK to disarm.

The deadly fighting has cast a shadow also on Turkish efforts to mend fences with the Iraqi Kurds, whom Ankara had often accused in the past of tolerating the PKK in their autonomous region in northern Iraq.

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 more than 40,000 lives.