The warning from the outlawed Kurdistan Workers' Party (PKK) followed Turkish press reports that thousands of additional troops had been deployed in the southeast of the country to intensify operations against Kurdish rebels, who have increasingly begun to infiltrate the region from across the border in northern Iraq.

"We believe the preparations are for a cross-border operation into northern Iraq," Zubeyir Aydar, the head of KONGRA-GEL, the PKK's political wing, told AFP in a telephone interview from Brussels.

"There are only a few thousands (PKK) guerillas at most in southeastern Turkey. It does not make much sense to move so many troops and equipment into the region for them," he said.

Aydar stressed that PKK rebels had made the necessary preparations and would "continue their struggle on the basis of active legitimate defence" against a possible cross-border operation.

"Turkey will suffer from such an operation. It would only lead to more death and pain," he added.

Turkey says an estimated 5,000 PKK militants have found refuge in the mountains of northern Iraq since 1999, when the group declared a unilateral truce following the capture of its leader Abdullah Ocalan.

Violence in the southeast, which has a majority Kurd population, has increased markedly since June 2004, when the PKK called off its five-year truce and the rebels started to cross the border for attacks on Turkish soil.

Turkish newspapers reported on Friday that the Turkish military had dispatched an additional 10,000 troops to the southeast for security operations, bringing to 50,000 the total number of soldiers there.

The reinforcements had been deployed in areas along the borders with Iran and Iraq, the press said.

Prior to the US-led occupation of Iraq, the Turkish army carried out frequent incursions into northern Iraq to pursue the PKK.

Since the Iraqi war, Ankara has repeatedly urged the United States to crack down on PKK bases in northern Iraq. But Washington says its troops are swamped by violence in other parts of the country.

More than 37,000 people have been killed since 1984, when the PKK, blacklisted by Turkey, the United States and the European Union, took up arms for self-rule in the southeast.