Several F-16 warplanes loaded with bombs took off from an air base in southeastern city of Diyarbakir, private Dogan news agency and local reporters said.

U.S.-made Cobra and Super Cobra attack helicopters chased Kurdish rebels some 3 miles into Iraqi territory on Sunday but returned to their bases in Turkey after a rebel ambush killed 12 soldiers near the border, the official said on condition of anonymity because he was not authorized to speak to the media.

He also said Turkish artillery units shelled rebel positions as recently as Tuesday night but did not say which areas were targeted and refused to give further information.

Turkey, which had moved troops to the Iraq border, warned Iraq and Western allies on Tuesday that a Turkish incursion is imminent unless the U.S.-backed government in Baghdad takes action and said there would be no cease-fire with the separatist fighters.