Ankara: Turkish troops have crossed into northern Iraq in their hunt for Kurdish PKK militants, the military said on Friday, but the United States and the European Union urged Ankara to keep the campaign limited.

The White House said the United States had been informed in advance of the incursion and urged Turkey to limit the operation to "precise targeting" of the PKK rebels hiding there. "We have strongly urged the Turkish government to bring any ongoing operations to a swift conclusion," Pentagon spokesman Bryan Whitman told reporters.

Turkish TV said 3,000 to 10,000 soldiers had entered Iraq, but Iraq's foreign minister and a senior military official with coalition forces based in Baghdad denied it was a major operation, saying only a few hundred troops were involved.

The European Union repeated its call for Turkey, which is seeking EU membership, to refrain from any disproportionate military action. "The Turkish Armed Forces, which attach great importance to Iraq's territorial integrity and stability, will return home in the shortest time possible after its goals have been achieved," the General Staff said in a statement posted on its website. The General Staff did not specify the size of the operation.

A military source in Turkey said: "Thousands of troops have crossed the border and thousands more are waiting at the border to join them if necessary." A PKK spokesman said rebels were battling the troops.

Severe clashes

"There are severe clashes. Two Turkish soldiers have been killed and eight wounded. There are no PKK casualties," Ahmad Danees, head of foreign relations for the PKK, told Reuters by satellite phone from an undisclosed location in northern Iraq.

Iraq's foreign minister played down the operation. "There has not been any major incursion or land invasion ... What is going on is around a few hundred Turkish forces have crossed the border looking for the PKK or their bases," Hoshiyar Zebari said.

Iraq's Prime Minister Nouri Al Maliki urged his Turkish counterpart Recep Tayyip Erdogan to respect Iraq's sovereignty, and Zebari said that Turkey's charge d'affaires in Baghdad had been summoned to receive a protest.

Zebari said information from the mountainous and snow-bound border area was sketchy, and he could not confirm reports of clashes or casualties but he said that Turks had demolished five bridges on the Avashin or Blue River.

Erdogan said he had briefed US President George W. Bush by telephone on the land offensive, which began at 7pm on Thursday.

But a senior US State Department official said the land incursion was "not the greatest news".