Turkey has massed some 100,000 troops on the border since the Turkish parliament last month approved a resolution allowing the government to order military strikes on Kurdish rebel bases in Iraq.

The Turkish military general staff said four soldiers, one of them an officer, were killed and two wounded in fighting with Kurdistan Workers' Party (PKK) rebels on Mount Kupeli, in Sirnak province.

A military statement said the clashes erupted during an anti-PKK operation.

The statement said troops were sweeping the Mount Kupeli area after a battle that lasted for more than 90 minutes.

"Other units are blocking the likely escape routes of the terrorists", it said, referring to the PKK.

The NTV news channel reported heavy losses on the PKK side, but the army did not detail rebel casualties.

Turkish warplanes were also reported to have targeted three villages near the border town of Zakho in Iraq's autonomous Kurdish region, a security official on the Iraqi side said. No casualties were reported.

The pre-dawn bombings targeted villages known to be frequented by PKK fighters in the Batoufa and Darkar districts, the Kurdish official told AFP on condition of anonymity.

Jamal Abdallah, a spokesman for the Kurdish regional government, denied that any bombings had taken place.

Yesterday evening Turkish planes dropped flares on border areas near Zakho. We do not know the reason why they dropped flares. There was no air strike or bombing. But an abandoned police outpost was shelled," Abdallah told AFP.

The Turkish general staff did not comment on the reports and Prime Minister Recep Tayyip Erdogan told reporters he was "not aware" of any Turkish air strikes inside Iraq, as reported by the Turkish media.

Pressure on the government to launch a major cross-border operation has increased since an October 21 PKK ambush on a Turkish military unit near the Iraqi border resulted in 12 troops killed and eight captured.

The captive soldiers were released on November 4, but were arrested a week later and now face a court martial on charges of neglect of duty and gross insubordination.

The tribunal handling the case has imposed a news blackout on the trial, citing national security concerns and said the soldiers would be tried for "acting contrary to the requirements of civil service duty, persistent insubordination resulting in great loss, and escaping abroad."

The tribunal said the soldiers "abandoned their positions in conformity with terrorist appeals and went to terrorist camps in northern Iraq along with the terrorists."

More than 37,000 people have been killed since 1984 when the PKK started a violent campaign for self-rule in southeast Turkey. It has since been listed as a terrorist group by much of the international community.

Turkey has said it has no choice left but military action because Iraq and the United States have not done enough to curb PKK activities on the Iraqi side of the border.

It says the PKK enjoys safe haven in northern Iraq and obtains weapons there to launch attacks on Turkish territory.

Last week, US President George W. Bush promised Turkey "live intelligence" to strike at the PKK after talks at the White House with Turkish Prime Minister Recep Tayyip Erdogan.

Iraqi leaders, pledging action against the PKK, have closed down the offices of PKK-affiliated groups and blocked roads leading to their camps, but Turkey says it is keeping the military option open.