Helicopter gunships bombed Kurdish rebel positions in southeast Turkey and the government flexed its military muscle with big national day parades and flypasts in major cities.

Turkey has massed up to 100,000 troops, backed by tanks, artillery, warplanes and combat helicopters, along the Iraqi border in readiness for a possible large-scale incursion to hunt down 3,000 guerillas who use northern Iraq as a base.

The White House said it was pressing Turkey and Iraq to keep up talks aimed at averting a major cross-border operation.

Witnesses said they saw helicopters firing rockets and bombing suspected Kurdistan Workers Party (PKK) positions in the mountains in Turkey's border province of Sirnak to prevent dozens of PKK rebels from crossing into northern Iraq. The operation, reinforced by ground troops to clear suspected PKK hideouts, was still going on after several hours.

Three soldiers were killed during the operation, CNN Turk reported. Another soldier was killed in Tunceli province, hundreds of kilometres from the border, by a landmine, a device favoured by the outlawed PKK.

As Turkey prepares for a cross-border offensive its military has also launched an extensive operation against suspected PKK positions in several provinces in the mainly Kurdish southeast.

On Sunday, army sources said 20 PKK guerillas had been killed in the Tunceli campaign involving 8,000 soldiers.

In Ankara warplanes swooped, tanks rolled and troops marched past President Abdullah Gul, Prime Minister Tayyip Erdogan and senior generals in a display of military might. Turkey has the second biggest armed forces in Nato.

Istanbul, Turkey's largest city and business hub, also staged a military parade and flag-waving patriots clapped loudly as tanks drove past. Many people carried pictures of Mustafa Kemal Ataturk, who founded modern Turkey in 1923.
 
'I am very proud of the 84 years of the Turkish Republic. We are not worried about the future. We are together and the republic will survive,' said war veteran Ahmed Kendigel, 52.

'It is our government's decision whether to go into northern Iraq but we are ready for anything. The army, the people, all of us are ready.'

Nationalist fervour has been rising, and the funerals last week of the 12 soldiers killed by the PKK turned into huge anti-PKK rallies that greatly increased the pressure on the  government to send troops into mainly Kurdish northern Iraq.

'With the news of ... dead soldiers, it is more important to celebrate today than ever. We need to show today we are against the PKK and terror attacks,' said student Reyhan Turan, 24.

'Turkey is on the threshold of historic decisions,' said the Vatan daily, which like most newspapers carried a large picture of Ataturk against a background of Turkish flags.

'We are passing through a critical period. And in these days, as Ataturk showed us many years ago, we need unity and solidarity,' it said in a front-page commentary.

Washington and Baghdad have urged Ankara to refrain from major military action in Iraq, fearing this would destabilise the wider region. Turkish-Iraqi talks aimed at averting a cross-border operation broke down on Friday.

'We obviously are encouraging the Iraqis and the Turks to continue having discussions,' said White House spokeswoman Dana Perino. 'They need to continue to apply pressure to the PKK.'

Iraqi Foreign Minister Hoshiyar Zebari said in an interview that a Turkish offensive would have 'disastrous' consequences for stability in both countries and the region.

Turkish officials say talks next Monday between Erdogan and President George W. Bush will be crucial in determining whether Turkey does carry out a major offensive into northern Iraq. Reuters