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

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 the other key oil centre of Kirkuk 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 reached a government building, but hastily withdrew after coming under sniper fire.

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

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 that such buildings were the main target of the 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 an Iraqi missile-launching base. Like Kirkuk, it had been the target of US air raids since the war in Iraq began on March 20.

Kurdish fighters who entered the city earlier Friday were given a subdued reception, unlike Kirkuk, which has deeper Kurdish roots and exploded in celebration Thursday at the arrival of peshmergas from the KDP's rival, the Patriotic Union of Kurdistan.

Kurdish forces were seen in only small numbers here around mid-morning, and though they seemed to be in control they later disappeared from the centre, and only a few were guarding bridges and some roads elsewhere in the city.

The yellow flag of the KDP, which had been hoisted on the city hall, was soon taken down and people were seen spreading out the Iraqi flag instead.

At the start of the day, there was also no sign of the US forces which officials had said were already in Mosul.

"Mosul and Kirkuk have fallen," Major Rumi Nielson-Green told AFP at the US Central Command base in Qatar. "Coalition forces are inside the cities," she said, adding "they are mostly special operations forces."

Dozens of residents gathered outside the city hall, and the looting already familiar in other places abandoned by Saddam's regime began.

A bank was also looted, with some looters making off with sacks full of the almost worthless Iraqi dinar notes which carry Saddam's face, while others played with the money in the streets.

In several districts of the city people were seen taking furniture and anything else they could carry from official buildings, some of which were later seen burning.

But other administrative centres, including the intelligence headquarters, were already destroyed, apparently by US-British coalition bombing.

One young man, Safah Salam, accused the peshmerga of looting. "Is that ensuring security, is that helping to stabilise the city?" he demanded.

Witnesses said the peshmergas had entered the city overnight, after Iraqi forces withdrew late Thursday, abandoning their weapons.

"The electricity was cut off at 10:00 pm (1800 GMT), they changed into civilian clothes," said one resident, Fariz Abbas. "The officers left for surrounding villages."

"The Iraqi soldiers have abandoned their weapons and gone home," added another witness, Hussein Said.

CNN reported that thousands of unarmed Iraqi soldiers had already abandoned positions in northern Iraq and were walking south, away from Kirkuk and Mosul, and US spokesman Brigadier Vincent Brooks said that the 5th Corps was now out of the war and was expected to disband and go home.

The fall of Kirkuk and Mosul to the PUK and KDP, who advanced from the autonomous northern Iraqi Kurdistan enclave they jointly rule, alarmed Turkey, which fears Kurdish control of the oil-rich region would fan desires for independence that would spread to its own restive Kurdish minority.

Washington responded by dispatching troops to both cities, and agreeing that Turkey could send observers into the region on Friday.

General "Mam" Rostam, a PUK commander, said his peshmergas had been ordered to leave Kirkuk once US forces arrived, and later reports said they were on the move.

SPACE.WIRE