Turkish helicopters later bombed villages in northern Iraq where Kurdish fighters are suspected to be hiding, two Turkish television channels reported.
 
CNN Turk television, quoting Iraqi officials, said the villages had been empty at the time.

Border tension

A senior Kurdish security official in northern Iraq said he was not aware of any Turkish attacks on Tuesday.

A PKK official also said he had not heard of any attacks.

Asked in parliament about the report that PKK bases in northern Iraq had been bombed, Tayyip Erdogan, the Turkish prime minister, said: "I am not aware [of that]."

Large numbers of Turkish troops are massed in Sirnak province for a possible major ground raid into northern Iraq to root out PKK fighters believed hiding there.

The death of the four soldiers on Tuesday is likely to increase pressure on the government to authorise a cross-border operation, despite the prospect of logistical difficulties in the coming winter.

Self-defence claim

Ankara claims the right of self-defence under international law to attack the PKK inside Iraqi territory.

It has already launched limited cross-border operations against the PKK, which has an estimated 3,000 fighters in northern Iraq.

George Bush, the US president, last week pledged to provide Turkey with real time intelligence on the PKK after talks with Erdogan in Washington.

The PKK started its campaign in 1984 to create an ethnic homeland in mainly Kurdish southeast Turkey.

About 37,000 people have been killed on both sides during the conflict.