The explosion was the latest episode in mounting violence between the army and the outlawed Kurdistan Workers' Party (PKK) with the arrival of spring, which allows the rebels to move around the mountainous region more easily.

Monday's home-made bomb exploded near the border village of Daglica, Hakkari province, during a security sweep launched Friday after a PKK attack on a military post in the region, said the source, speaking on condition of anonymity.

Following Friday's attack, which left two soldiers and five rebels dead, Turkish helicopter gunships pounded targets in northern Iraq where the PKK has rear bases.

The Turkish army has staged a series of air raids across the border since December 2007, often with the help of US intelligence, and in February 2008 carried out a week-long ground incursion.

In October 2007, Daglica was the scene of one of the bloodiest PKK attacks in recent years in which rebels sneaking in from Iraq ambushed a patrol, killing 12 soldiers and wounding 17 others.

The PKK, listed as a terrorist group by Turkey and much of the international community, took up arms against Ankara in 1984, sparking a conflict that has claimed about 45,000 lives.