Kurdistan Workers Party (PKK) militants killed two soldiers and wounded 31 in a suicide attack overnight in eastern Turkey, the army said on Sunday, as violence escalated following Ankara's air bombardment targeting Kurdish militants.

PKK militants drove a tractor filled with explosives into a military outpost in the Dogubeyazit district of the eastern Agri province bordering Iran, the army said in a statement.

Four of the wounded were in serious condition, it said.

The PKK also attacked a unit on patrol in the southeastern province of Mardin late on Saturday night, killing one soldier and wounding seven, the army said.

The PKK announced it was stepping up attacks in mid-July over what it said were ceasefire violations, but has responded with yet more violence since Turkey began a campaign of air strikes on PKK camps in northern Iraq on July 24, in what the prime minister has called a "synchronised fight against terror".