Eleven vehicles carrying dozens of US troops reached Mosul from the north along the Dahuk road, followed by around 300 Kurdistan Democratic Partypeshmerga fighters.

They drove through empty streets amid devastation caused by a day of looting after the city's fall, which came a day after Iraqi forces also abandoned Kirkuk, another key oil centre 180 kilometres (110 miles) to the southeast.

The US and Kurdish troops went to the home of Sheikh Ibrahim Attallah al-Juburi, who heads Iraq's most powerful tribe, and then to a government building, but hastily withdrew after coming under sniper fire, an AFP correspondent said.

Earlier, US and KDP officials said commanders of the Iraqi army's 5th Corps based on Mosul had signed a ceasefire accord with the US military, effectively surrendering.

The move left President Saddam Hussein's ancestral power base of Tikrit, 220 kilometres (135 miles) south of Mosul, as his regime's last major holdout following the seizure of Baghdad on Wednesday by US forces driving up from Kuwait.

An Iraqi opposition figure, Mashaan al-Juburi, told Al-Jazeera television, "We want to install order and protect official buildings in Mosul very quickly," noting such buildings were the main target of widespread looting.

"All the Arab tribes and the inhabitants of Mosul are involved in this operation, organised with the agreement of the American soldiers."

Mosul, located 450 kilometers (280 miles) north of Baghdad, is an Arab-majority enclave of 1.5 million inhabitants in the mostly Kurdish north and surrounded by oil fields.

It is strategically important because of its airport and a missile base, and was the target of US-British coalition air raids from the beginning of the war in Iraq on March 20.

Kurdish fighters who entered the city in small numbers earlier Friday kept a low profile and were given a subdued reception, unlike in Kirkuk, which exploded in celebration Thursday at the arrival of peshmergas from the KDP's rival, the Patriotic Union of Kurdistan (PUK).

Dozens of residents gathered outside Mosul city hall, and the looting already familiar in other places abandoned by Saddam's regime began. People were seen anything they could carry from official buildings, some of which were later seen burning.

Other administrative centres, including the intelligence headquarters, were already destroyed, apparently by coalition bombing.

Meanwhile US troop reinforcements headed Friday to Kirkuk with orders to secure the city, said Barham Salah, the Kurdish "prime minister" of the PUK's area of the autonomous zone of northern Iraq it administers with the KDP.

Hundreds of Kurdish policemen had already arrived in Kirkuk to restore order after the situation began spinning out of control overnight, an AFP reporter saw.

Salah said PUK peshmergas who captured the city along with US special forces Thursday would withdraw "as quickly as possible, but not before a sufficient number of American troops have arrived."

Talks were being held to finalise details of the Kurdish pullout and the installation of a provisional administration included representatives of Kirkuk's various ethnic communities and senior US officers.

After a night of ceaseless looting, Rizgarali Hamgam, installed as provisional governor by the Kurds following the seizure of Kirkuk, admitted, "We cannot control the situation."

Looters who followed the peshmergas into Kirkuk made off with lorry loads of booty, while hardly a drop of petrol could be found.

Hamgam said a number of people had been killed or wounded in personal or ethnic score-settling, but one of the city's main hospitals said it had admitted no such cases.

Historically a Kurdish-majority city, Kirkuk was "ethnically cleansed" under the rule of Saddam Hussein, whose forces expelled many of its original inhabitants and replaced them by Arabs.

Thousands of Kurdish exiles flooded back in on Thursday, vowing to reclaim their confiscated property, by force if necessary, sparking fears among city's Arab and Turkmen residents.

A furious Turkey, which fears Kurdish dominance of the north would arouse separatist aspirations among its own Kurdish minority, said Thursday it had won a US pledge to drive out the Kurdish fighters from Kirkuk.

General "Mam" Rostam, a PUK commander, told AFP Friday that some 10,000 peshmergas in the city had been ordered to leave anyway. "We are waiting now for the US forces to arrive. The armed peshmergas should leave the city today or tomorrow," he said.

Washington was keen to keep Turkey out, fearing clashes between the Turkish army and Kurdish groups, both US allies.

In a compromise deal with the United States, Turkey on Friday sent about 15 military observers to northern Iraq to monitor developments, a senior diplomat in Ankara said.

"They will stay there as long as necessary," he added, while a government statement said the observers would cooperate with US units in the area.

SPACE.WIRE