Turkish attack helicopters have fired at Kurdish rebel positions in a southeastern border region for a second day.

Turkish helicopter flies over Cudi mountain during attack on Kurdistan Workers Party (PKK) camp, 30 October 2007

Witnesses say the helicopters flew over a mountain in Sirnak province early Tuesday, and soon afterwards black smoke was seen rising in the sky.

Turkey's state media said at least four soldiers have been killed in the fighting that erupted early Monday, when Turkish forces surrounded about 100 Kurdish rebels near the border.

Turkey's foreign minister says all options remain open in the fight against Kurdish rebels and terrorists based in northern Iraq.

In an interview with the BBC, Iraqi Foreign Minister Hoshiyar Zebari warned about "disastrous consequences" if Turkey launches an incursion into northern Iraq to pursue the rebels with the Kurdistan Workers' Party, or PKK.

Turkey accuses Kurdish rebels of using bases in northern Iraq to launch attacks into southeastern Turkey.

The European Union and the United States are pressing Ankara not to invade northern Iraq to pursue the rebels.

Some information for this report was provided by AP and Reuters.