Turkish helicopter gunships attacked abandoned villages inside Iraq on Tuesday, Iraqi officials said, the first such airstrike since border tensions have escalated in recent months. It also was the first major Turkish action against Kurdish rebels since Turkish Prime Minister Recep Tayyip Erdogan met President Bush in Washington earlier this month. The United States and Iraq have pressured Turkey to avoid a large-scale attack on rebel bases in northern Iraq, fearing such an operation would destabilize what has been the calmest region in the country. Meanwhile, Kurdish guerrillas killed four Turkish soldiers in a clash Tuesday in southeastern Turkey, Turkish Defense Minister Vecdi Gonul said.

More than 50 Turkish troops have been killed in a series of hit-and-run attacks by Kurdish rebels since late September. Turkey says it has killed dozens of rebels.

Col. Hussein Tamir, an Iraqi Army officer who supervises border guards, said the airstrikes occurred before dawn on abandoned villages near Zakhu, an Iraqi Kurdish town near the border with Turkey. There were no casualties, he said.

A spokesman for the Kurdistan Workers' Party, or PKK, corroborated Tamir's account of the airstrikes, and said sporadic clashes had been taking place inside Turkey since late Monday. He spoke on condition of anonymity because he was not authorized to speak to media.

Witnesses said the Turkish bombing lasted half an hour in the villages of Nazdori, Kashani and Baashish.

"I was on the other side of the mountain when I heard huge explosions and could smell TNT powder all over the area," said 53-year-old Irbahim Mazori. A shepherd, Mazori said he sometimes spends a night or two in the villages while tending his sheep.

U.S. authorities have agreed to share intelligence about positions of Kurdish rebels with Turkey, possibly enabling the Turkish military to carry out limited assaults.

"The United States has declared the PKK as the common enemy. The struggle against this enemy will be maintained until it is eliminated," Erdogan told lawmakers in Parliament Tuesday.

Tens of thousands of Turkish troops have massed in the country's southeast ahead of a possible operation in Iraq.

Kurds are a major ethnic group straddling four Middle Eastern countries - Turkey, Iran, Iraq and Syria - totaling about 20 million people. Most live in Turkey, primarily in the southeast, where the PKK has been fighting for autonomy since 1984 in a conflict that has killed nearly 40,000 people.