The rebel Kurdistan Workers' Party (PKK) said on its website that its guerrillas were behind an armed attack on a police van in the city of Batman on Monday, in which three officers were killed and four others wounded.

The group also claimed an armed attack on a military vehicle in Cizre, a town near the borders with Iraq and Syria, last Thursday, which killed one soldier and injured three others.

The attacks, it said, were carried out to avenge the killing of seven PKK militants in a major army operation in the province of Mardin in late February.

Unrest in the predominantly Kurdish southeast has significantly escalated since June 2004 when the PKK called off a five-year unilateral ceasefire.

A radical Kurdish group which officials say is a cover-up for the PKK has also claimed deadly bomb attacks on civilian targets in western Turkey.

The Kurdish conflict has claimed 37,000 lives since 1984 when the PKK, blacklisted a terrorist group by Turkey as well as the European Union and the United States, took up arms for Kurdish self-rule in the southeast.