More than 150 Kurdistan Workers' Party (PKK) fighters have been killed in northern Iraq, Turkey's military has said, as fighting in northern Iraq enters a sixth day.

The Turkish army said on Tuesday that 17 of its fighters have also died since Thursday.

The PKK, which Ankara says has 4,000 men in the area, had rejected the death toll and says it has killed 81 soldiers.

The Iraqi government has said it fears that a prolonged military operation could lead to clashes with its own Kurdish security forces.

Earlier on Monday, clashes broke out in the southern Turkish city of Diyarbakir between police and Kurds demonstrating against the offensive.

'Sovereignty violated'

Turkish fighter jets hit up to 30 targets deep in northern Iraq on Monday on the route of the Turkish advance as helicopter gunships and artillery maintained intense fire throughout the day, the army said.

Turkish soldiers fired more than 40 salvos of artillery shells across the Iraqi border.

Iraqi security forces in autonomous Kurdish-administered northern Iraq said jets bombed areas in and around Hakurk from 2000 GMT Sunday to 1100 GMT Monday until rains, strong winds and a heavy fog

settled over the area.

Hoshyar Zebari, Iraq's foreign minister, said the operation was a violation of Iraq's sovereignty.

"This is a serious escalation of events, and it is extremely worry and destabilising for our country," he told Al Jazeera.

"We have asked the Turkish government to order its troops to withdraw as soon as possible."

Ankara's assurances

Washington said it hoped the offensive would be short-lived and avoid harming civilians.

Dana Perino, a White House spokeswoman, said: "We hope that this is just a short-term incursion."

Turkey gave fresh assurances on Monday that its forces will retreat once it achieves its objective of flushing out the fighters, but offered no precise timeframe.

James Bays, Al Jazeera's correspondent, was given exclusive access to Dashta Takh area in northern Iraq, by the Kurdish regional government.

"They wanted to show the world that there are no PKK fighters in this area," Bays said.

"We have not been able to scour the moutainside but we have not seen any PKK positions."

Diyarbakir protest

A demonstration by Kurds against the offensive in Diyarbakir on Monday turned violent when the crowd threw stones at police.

Police retaliated by throwing tear gas and firing into the air in an attempt to disperse the crowd.

On Sunday, a PKK fighter commander had urged Kurds living in Turkish cities to rise up and fight the authorities.

As the battles in northern Iraq raged, senior Turkish leaders joined thousands of mourners in Ankara for the funeral of three officers killed in the offensive.

Two of those killed were the pilots of a helicopter that the army said was "destroyed" near Amadiyah, without giving any details.

The PKK said on Sunday that it had downed a Turkish attack helicopter.

The mourners chanted "Damn the PKK," "The motherland will never be divided," at the ceremony attended by Abdullah Gul, Turkey's president, and Recep Tayyip Erdogan, the country's prime minister.

The PKK is fighting for autonomy in predominantly Kurdish southeastern Turkey and have carried out attacks on Turkish targets from bases in the semi-autonomous Kurdish region of northern Iraq.

Started in 1984, the conflict has claimed as many as 40,000 lives.

PHOTO CAPTION

A Turkish army commando patrols a road surrounded by snow-capped mountains between Sirnak and Hakkari in the southeast Turkey, bordering Iraq, February 25, 2008.

Al-Jazeera