US begins its biggest urban offensive since Vietnam with long-awaited Fallujah assault

The American assault on Fallujah, the stronghold of Iraqi insurgents, finally began last night in what is expected to be the biggest urban assault by US forces since Vietnam.

The American assault on Fallujah, the stronghold of Iraqi insurgents, finally began last night in what is expected to be the biggest urban assault by US forces since Vietnam.

After a day which saw US warplanes bombarding the city with 500lb bombs, incursions began about 7pm local time with marines moving into the city through a number of routes and seizing rebel-held territory.

In the early hours of this morning, a tank company and infantry unit moved to a staging area near Fallujah. Witnesses said there was heavy fighting on the eastern and western fringes of the city. US forces were reported to have taken over the main hospital.

Sources say there will not be a full offensive on Fallujah. Instead, US forces and their Iraqi allies will take the city section by section by clearing houses. The operation is intended to take no more than two weeks.

The US military, with the fledgling Iraqi security forces in tow, hopes the Fallujah offensive will deal a heavy blow to the insurgency, creating sufficient stability for the elections in January. Many of the attacks on the international forces and members of the Iraqi government are thought to have been organised from the city, which is thought also to be the base of Abu Musab al-Zarqawi, the insurgent ringleader. The insurgents say they will counter with escalating violence.

There has also been criticism that the assault has been so long coming, amid suspicion that it was delayed to avoid damaging headlines about civilian casualties in the run-up to the US Presidential election.

But the offensive will be controversial. There are fears that significant numbers of civilians will be killed in the process. British troops have for the first time been moved to the north of Iraq to free up American forces for the assault. It is understood that British soldiers sealed off a bridge over the Euphrates yesterday to prevent insurgents using it to make their escape from Fallujah.

Earlier US troops announced they had "isolated Fallujah" and all traffic into and out of the city had been halted.

Government negotiators reported the failure of last-minute peace talks as Iyad Allawi, the interim Prime Minister, maintained that dialogue with Fallujah leaders was still possible. Mr Allawi, a secular-minded Shia Muslim, faces strong opposition from within the minority Sunni community to avoid an all-out assault. The UN secretary general, Kofi Annan, has voiced fears that an assault could trigger a wave of violence that could jeopardise the January elections.

US commanders pumped up troop spirits yesterday. Standing before some 2,500 marines, who stood or knelt at his feet, Lt-Gen John F Sattler, the commanding officer of the 1st Marine Expeditionary Force, told them that they would be at the front of the charge. "This is America's fight," Lt-Gen Sattler said. "What we've added to it is our Iraqi partners. They want to go in and liberate Fallujah. They feel this town's being held hostage by mugs, thugs, murderers and terrorists."

Two marine battalions, along with a battalion from the army's 1st Infantry Division, will be the lead units sent into a Fallujah attack. They will be joined by two brigades of Iraqi troops.

More than 10,000 US troops massed around the Sunni Muslim city are expected to take a role in the assault on Fallujah, whose green-lit minarets are visible from the US base near the city. Sgt Major Carlton W Kent, the senior enlisted marine in Iraq, told troops that the coming battle of Fallujah would be "no different" to the historic fights at Inchon in Korea, the flag-raising victory at Iwo Jima, or the bloody Tet Offensive to remove North Vietnamese from the ancient citadel of Hue in 1968. "You're all in the process of making history," he told them. "This is another Hue city in the making. I have no doubt, if we do get the word, that each and every one of you is going to ... kick some butt."

The US Marines battalion commander Lt-Col Mike Ramos said many would be going into combat for the first time.

Despite the grisly evidence of earlier US offensives against the insurgents, Lt-Col Ramos, 41, of Dallas, predicted that "freedom and democracy" would prevail in Fallujah within days. "Make no mistake about it, we'll hand this city back to the Iraqi people," he said.

Rules of engagement allow US troops to shoot and kill anyone carrying a weapon or driving in Fallujah, so US troops can fire on car bombers, Lt-Col Ramos said. Military-age males trying to leave the city would be captured or turned back.