An AFP correspondent said the streets were calm and that five armored vehicles were in the city center, which appeared to have been deserted by Iraqi regular forces and much of the population.

The vehicles were deployed in a main square of the town, 180 kilometres (115 miles) north of Baghdad, after US Marines entered it before dawn, a sergeant said.

"We didn't encounter any resistance in the city, but only on the outskirts last night. We had bad ambushes there," said Marine Sergeant Robert Chute.

Firefights with what Chute believed to be Iraqi soldiers had left at least one Iraqi dead, while US units reported no casualties.

"My feeling is this means the end of the war" Chute told journalists in Tikrit, Saddam's hometown and a traditional stronghold of his Baath party located 180 kilometers (115 miles) north of Baghdad.

At the US Central Command's war headquarters in Qatar, British Group Captain Al Lockwood was equally upbeat. "As far as I am aware, Tikrit is the only pocket of resistance ... and so there is a very good chance that once Tikrit has fallen the war will have finished," he said.

"Clearly we are at a point when the decisive military operations that were focused on removing the regime ... that work is coming to a close," US Central Command spokesman Brigadier-General Vincent Brooks said.

"We believe our decisive operations campaign will be measured in weeks not months," he said.

Outside the center of Tikrit, witnesses reported gunfire as residents warded off looters, but there was no immediate confirmation of the report.

US troops aboard four helicopters landed near the Tikrit headquarters of Saddam's Fedayeen militia but encountered no resistance, witnesses said.

Tribal chiefs had sought to negotiate a peaceful entry by coalition troops, but intermittent air strikes could be heard on the city's outskirts throughout the night.

A Canadian journalist with the US Marines told CNN that the 250 US armoured vehicles which entered the city had met some resistance from loyalist forces.

He quoted a US commander as saying five Iraqi tanks had been destroyed on the outskirts of the city and at least 15 people killed in firefights.

However the fighting fell well short of the feared last stand by Saddam's closest tribal allies.

"The Iraqi military appears to be over as an organized fighting force," Captain Frank Thorp told reporters at Centcom's As-Saliyah forward base.

"But it is premature to say the war is over as long as there continues to be resistance," he said.

"This morning, the attack entered Tikrit, securing the presidential palace and beginning to search for any regime supporters," Brooks also said.

"This really was the only significant combat action that occurred in last 24 hours."

There were still sporadic bursts of fighting in Baghdad, where Marines exchanged fire with unidentified targets around the Palestine Hotel in the city center overnight, AFP journalists reported.

The Marines occasionally opened fire with automatic weapons and fired flares around the hotel, which houses most foreign media in the Iraqi capital.

In London, Defense Secretary Geoff Hoon said he believed that resistance to US-led forces in Baghdad was led by "foreign suicide bombers."

Meanwhile US troops were trying to maintain some order in Baghdad, wracked by days of looting since Saddam's 24-year grip on the Iraqi capital collapsed last week.

A US military spokesman said US troops would start joint patrols with Iraqi security forces. US officials have begun trying to rebuild the Iraqi police force as well as drawing people back to key sectors such as the electricity department.

In the main northern cities of Mosul and Kirkuk, calm had returned Sunday after two days of looting and intercommunal fighting, with US troops reassuring Turkey by replacing Kurdish fighters in the oil-rich cities.

Mosul police were back on the streets while vigilantes were also trying to restore order in the city of 1.5 million, where as many as 20 people were killed and 200 wounded in two days of fighting between Arabs and Kurds.

Kurdish residents and members of the Free Iraqi Forces -- part of the US-backed Iraqi National Congress (INC) umbrella opposition group -- were sharing the task of protecting the city's infrastructure, US military sources said.

The situation was similar in Kirkuk, the other northern oil hub, where calm was slowly returning to the streets.

In the south, British troops were beginning joint police patrols with Iraqis in the city of Al-Fao, a reporter said.

In central Iraq, a group of about 50 gunmen surrounding the Najaf home of top religious authority have withdrawn following the intervention of several tribal chiefs, a Kuwaiti Shiite cleric said.

He said the intervention by tribal leaders, who are mainly from the central Euphrates region, helped end the presence of the armed men who demanded that Ayatollah Ali Sistani leave the town.

Sistani reportedly has been moved to an undisclosed location in Najaf.

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