A London-based Muslim leader who supports al Qaeda warned on Thursday that the group was likely to stage a major attack against the United States and Britain if they launch a war on Iraq. "If Britain and the United States attack Iraq they will suffer heavy casualties back home," said Syrian-born Sheikh Omar Bakri Muhammad, leader of the Muslim al Muhajiroun group.

"If they fire their missiles on Iraq, an attack against Britain is inevitable," he told Reuters.

In a later interview with al-Jazeera television, Bakri warned Muslims to be careful in London on Friday.

"We (Muslims) must be careful in every aspect of our lives and I call upon the Muslim community to avoid vital places in Britain, especially as the anniversary of the first Badr conquest is coming, and to avoid politically and economically vital places in London to safeguard their lives," he said.

The first Badr conquest -- a seventh century battlefield victory for the early Muslims -- took place on the 17th day of Ramadan, which falls this year on November 22.

In his interview with Reuters, Bakri said a recent warning by British Prime Minister Tony Blair that the threat of terror attacks on Britain was "real" and that Osama bin Laden's al Qaeda could target the country should be taken very seriously.

"Blair correctly warned the British. Never before has there been such Muslim rage against the United States and Britain. It is not al Qaeda's style to carry out small attacks. They always select a powerful attack," he said.

"Al Qaeda proved its abilities on September 11. They will do something big," he said.

Three North African men charged under terrorism laws were remanded in custody in London this week as the government played down fears they could have been preparing a gas attack on the London underground rail network.

Britain has been a staunch ally of the United States in its war on terror following the September 11 attacks on U.S. cities, which the United States blames on al Qaeda. It has also backed Washington's tough line warning Baghdad it "will be disarmed by force" if it did not cooperate with U.N. weapons inspectors.

Iraq has promised full cooperation with a U.N. resolution demanding total disclosure of suspected arms programmes.

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Bakri caused outrage last October by calling Blair a "legitimate target" for Muslims and urging followers to kill anyone involved in military action against Muslims.

Police said then they had insufficient evidence to prosecute him for racial incitement, but would monitor his activities.

Bakri later said al Muhajiroun's Pakistan branch had described Blair as a legitimate target for Muslims, not him.

Active religious Muslim leaders in Britain have come under the spotlight since last year's attacks. Bakri is associated with Egyptian-born Abu Hamza al-Masri, who the United States links to bin Laden. Masri is wanted on terrorism charges in Yemen.

Masri has praised bin Laden, but denies any links to him.

Bakri said it would not be difficult for al Qaeda to operate in Britain because it has been actively recruiting supporters by sending agents to mosques and urging holy war through audio tapes and Internet sites.

"What they are trying to do is recruit supporters and influence groups to take up their cause and imitate their actions," he said. "The idea is that these groups become freelancers who decide on their own to join the al Qaeda phenomenon and carry out their own attacks modelled on al Qaeda."

PHOTO CAPTION

An active religious Muslim leader says Britain and U.S. vulnerable to al Qaeda attack - British Prime Minister Tony Blair and U.S. President George W. Bush exchange words during the afternoon session of the NATO summit in Prague on November 21. REUTERS/Kevin Lamarq