ANKARA, Turkey - Turkish troops on Sunday killed 15 separatist Kurdish rebels in a clash in southeastern Turkey, the private Dogan news agency reported.

The fighting reportedly occurred in the mainly Kurdish province of Tunceli, which is not near the border with Iraq where most of the recent clashes have occurred.

An official with the governor's office for Tunceli confirmed that Turkey's military was conducting a military offensive against the rebels at a rural area near the town of Pulumur, but would not provide any further details or confirm any casualty figures. He spoke on condition of anonymity because he was not authorized to speak to the media.

The government-run Anatolia news agency said the fighting began Sunday morning and the Turkish troops were backed by helicopter gunships. Security forces shut down a major highway leading to Pulumur it said. It did not mention any casualties.

Tunceli is some 550 kilometres northeast of the province of Sirnak and 650 kilometres northeast of the province of Hakkari, the places where most of the recent fighting with the rebels have taken place. Sirnak and Hakkari border Iraq.

Turkey's prime minister on Sunday, meanwhile, called for unity between Turks and Kurds, and reiterated his government's determination to fight Iraq-based separatist Kurdish rebels.

"As long as we are firmly bound together, the treacherous separatist terrorist attacks will never reach their goal," Recep Tayyip Erdogan said in a message ahead of Oct. 29 celebrations marking the 84th anniversary of the Turkish republic.

"I want to declare this one more time: the struggle we lead against the separatist terrorism that aims to destroy our unity and our constitutional order will continue with belief and determination," he said.

Turkey has been threatening to stage a cross-border military offensive into Iraq to hunt down the rebels who maintain bases there.

The conflict dates back to 1984 but clashes between government forces and guerrilla fighters have been escalating since the rebels broke a ceasefire in 2004.

Kurdistan Workers' Party, or PKK, fighters have killed at least 42 people in the past month. Those casualties included some 30 Turkish soldiers in two ambushes that were the boldest attacks in years.

Turkey's top military commander, Gen. Yasar Buyukanit, on Saturday promised to make the rebels "grieve with an intensity that they cannot imagine."

There is increased anger toward the PKK in Turkey, and tens of thousands of Turks have staged street protests in several Turkish cities condemning the guerrillas and pushing for action since last Sunday, when 12 soldiers were killed in a Kurdish rebel ambush. The PKK said it was holding eight other soldiers captive.

On Sunday, A 15-kilometre run across Istanbul's Bosporus bridge to the European side of the city turned into an anti-PKK protest, with thousands of runners waiving Turkish flags and shouting slogans denouncing the rebels.

"Down with the PKK," "every Turk is born a soldier," and "martyrs never die, the country will never the divided," they shouted.

A husband and wife in Istanbul also began a hunger strike to protest the PKK violence and demand the return of the eight Turkish soldiers, the government-run Anatolia news agency reported.

The PKK has indicated it is considering the release of the soldiers in response to calls by a lawmaker.

Military helicopters have been shuttling more troops to the mountains near Iraq, while patrols secure roads and checkpoints. The Turkish government has not said how many troops are now in place, but local media has been reporting between 100,000 and 150,000 soldiers are massed in the region, squaring off against some 3,000 to 4,000 PKK fighters.

The United States, Iraq and other countries have been pressing for Turkey to refrain from cross-border military operations.

A military campaign in Iraq could derail one of the few stable areas in Iraq, and leave the United States in an awkward position with key allies.

But talks between Iraqi and Turkish officials on Friday failed to produce any breakthroughs and the Iraqi delegation returned home on Saturday.