Explosions and gunfire were reported in and around Hakurk, a stronghold of the rebel Kurdistan Workers' Party (PKK), some 20 kilometres (12 miles) from the Turkish border.

More than a dozen Turkish warplanes could be seen heading for the area.

The PKK said Sunday it had shot down a Turkish attack helicopter, but there was no independent confirmation.

Turkish troops, backed by air support, moved into northern Iraq on Thursday evening in the largest cross-border offensive in years against PKK hideouts.

The United States cautioned its NATO ally that military measures alone could not resolve the Kurdish problem and stressed that the incursion needed to be completed as quickly as possible.

"The shorter the better," US Defence Secretary Robert Gates said Sunday.

Gates, who is due in Ankara next week, also urged Turkey to pursue political and economic measures that would win over its sizeable Kurdish community and erode popular support for the rebels.

"Just using the military techniques are not going to be sufficient to solve the problems," Gates said during a visit to Canberra.

The United States is providing its NATO ally with real-time intelligence on PKK movements.

At least 79 PKK fighters and seven soldiers have been killed and many rebel hideouts destroyed since Thursday, according to the Turkish military.

The PKK said 45 soldiers had been killed.

The Firat news agency, considered to be a PKK mouthpiece, reported air raids and fighting Sunday in the Zap area to the west and said about 5,000 Turkish soldiers and 60 tanks were advancing in nearby Haftanin, close to the border town of Zaho.

The Turkish army released pictures from the offensive, showing soldiers in white camouflage cloaks taking aim at unseen targets in snow-covered hills.

A senior PKK leader, Bahoz Erdal, called on Kurds across Turkey, especially those living in urban areas, to rise up in response to the offensive.

"If they want to wipe us out, our youths should make life in the cities unbearable," Firat quoted Erdal as saying. "Kurdish youths should unite ... and burn hundreds of cars every night".

Erdal also slammed the United States and Iraqi Kurds for helping Turkey.

"US reconnaissance planes are overflying the region. They instantly convey to the Turkish army information about the position of our forces and then Turkish warplanes come and bomb," he said.

He accused Iraqi President Jalal Talabani, also a Kurd, of having "invited" the Turkish army to the Qandil mountains along the Iraqi-Iranian border, where some of PKK's main camps are located.

The Qandil mountains were among the targets of air raids Saturday, according to Turkey's semi-official Anatolia news agency.

Despite earlier protests, Iraq's government spokesman said Sunday that Baghdad accepted the Turkish offensive posed no threat to its territorial integrity.

"We do not find these operations as an attack on Iraq's sovereignty... But we have told Turkey that the operation should not destabilise Iraq and the region," Ali al-Dabbagh told AFP.

Gates urged Ankara to be more open with Baghdad and Kurdish regional authorities about its plans after Iraq complained that it had only been informed of the operation "at the last minute".

Ankara says an estimated 4,000 PKK rebels are holed up in northern Iraq and use the region as a springboard for cross-border attacks as part of their campaign for self-rule in the Kurdish-majority region of southeast Turkey.

The conflict has claimed more than 37,000 lives since the PKK took up arms in 1984.

burs-su/gh