TONY BLAIR yesterday defended US tactics in the Iraqi city of Fallujah where American forces have been engaged in fierce fighting with Sunni militants.

The Prime Minister was speaking as the besieged city was rocked again by a series of explosions and gunfire - only hours after a heavy battle in which US warplanes and artillery pounded insurgents holed up in a slum.

Mr Blair told MPs at Prime Minister's Questions that the US military strategy was "essentially right".

The US decision to take on the militants was sharply criticised in a letter this week by 52 former British diplomats attacking the Government's support for US policy in Iraq and the Middle East.

Mr Blair said US troops had the right to defend themselves in the face of attacks by heavily-armed insurgents.

He said the vast bulk of the population in Fallujah wanted the militants to lay down their arms so that a peaceful settlement could be negotiated.

He was attacked by senior Tory backbencher Sir Peter Tapsell, who demanded to know whether the "murder or mutilation of hundreds of women and children" was an appropriate response to the murder of four American contractors in the city.

Mr Blair was also involved in heated exchanges with Michael Howard. He questioned the Tory leader's support for the military action in Iraq after Mr Howard tried to press him on the diplomats' letter.

Mr Howard insisted he did support the Government over action in Iraq, adding: "But if you think that somehow disqualifies me from asking perfectly legitimate and relevant questions about what is happening in Iraq now, then you grossly misunderstand the nature of our parliamentary democracy."

Mr Blair said: "At a time when coalition forces, including British forces, are engaged in trying to defeat these former regime elements and terrorists, and at a time when reconstruction in Iraq is going ahead - subject to this appalling attack by terrorists - I would have hoped you would actually support those forces and everyone in Iraq."

Meanwhile in Fallujah, despite three straight days of heavy fighting, US officials said they were pushing ahead with negotiations to resolve the stand-off rather than launch an all-out offensive.

Iraqi police took up posts in parts of the city, laying the groundwork for US marine patrols to establish control.

In southern Iraq, gunmen ambushed a Ukrainian convoy outside the city of Kut, hitting it with rocket-propelled grenades and machine-guns. One Ukrainian was killed and two wounded. A second coalition soldier later died from his wounds.

In northern Iraq, a US soldier was killed in an ambush on troops responding to a roadside bombing, the military reported yesterday.

The attack, on Tuesday, was near the city of Tel Afar, 240 miles north-east of Baghdad.

At least 725 US troops have died in Iraq since the war began in March last year. Up to 1,200 Iraqis have been killed this month.