ISTANBUL, Aug 2 (Reuters) - The Turkish army said two of its soldiers were killed and 31 wounded in an attack overnight by the Kurdistan Workers Party (PKK), as violence escalated following Ankara's air bombardment of Kurdish militants in northern Iraq. The suicide attack was carried out with a tractor loaded with two tonnes of explosives on a gendarmerie outpost in the Dogubeyazit district of eastern Agri province, bordering Iran, the provincial governor's office and the army said. Four of the soldiers injured in the attack in which PKK militants also used rifles were in serious condition, the army said. Another soldier was killed in Turkey's southeastern province of Mardin when a unit on patrol was attacked by the PKK late on Saturday night, the army said.