Yusuf al-Qaradawi, 79, who has a visa to come to Britian but is banned from entering the United States, has been asked to attend the conference in Manchester.

The invitation will be seen as the first test of the Government’s promise after the London bombings to clamp down on hardline Islamic preachers and other extremist clerics.

Charles Clarke, the Home Secretary, is expected to let Dr Qaradawi enter Britain despite having the power to ban him on the grounds that his presence is not “conducive to the public good” and is a threat to public order.

Dr Qaradawi is banned from the United States because of his pronouncements on suicide bombs and his links with the Muslim Brotherhood, believed to be the religion’s oldest fundamentalist organisation.

Home Office officials are aware that he has been invited to the conference at Bridgewater Hall, Manchester, on August 7. Mr Clarke is looking carefully at the case and in particular at Dr Qaradawi’s public statements on suicide bombings; but it is understood that at present he will not ban him from coming to Britain.

A Home Office spokeswoman said: “The Home Secretary has the power to exclude and most exclusions are on the grounds of national security or that someone’s presence would not be conducive to the public good.”

A total of 14 people were excluded from Britain in 2004, 12 of them on national security grounds. Among them was a Pakistani cleric who had a visa but had encouraged jihad at a mosque in Glasgow.

Dr Qaradawi visited Britain last year as a guest of Ken Livingtone, the Mayor of London. His presence drew protests from Jewish groups and gay rights organisations.

After the Asian tsunami, Dr Qaradwi said: “People must ask themselves why this earthquake occurred in this area and not in others. Whoever examines these areas discovers that they are tourism areas . . . where the forbidden acts are widespread, as well as alcohol consumption, drug use and acts of abomination.

“After the trafficking in drugs and trafficking in weapons comes sex tourism, in which prostitution and sexual perversion are traded. They even traffic in children. Don’t they deserve punishment from Allah?” He is among a number of controversial figures asked to speak at a Muslim Unity conference organised by the Ramadhan Foundation.

The event will be addressed by Dr Bilal Phillips, a Jamaican who was once associated with the Black Panthers and who in his youth contemplated training in guerilla warfare before converting to Islam.

Also speaking will be Abdullah Hakim Quick, a South Africa-based scholar, who has written at length on his website suggesting that the US Administration played a role in assisting the 9/11 terrorists. Dr Imran Waheed, the leader in Britain of the extremist Hizb ut Tahrir party, is another confirmed speaker.

Hizb ut Tahrir, which has a stated aim of establishing an Islamic state, is banned in Germany and many Arab countries but is flourishing among Muslim youth in Britain.

Dr Waheed said yesterday that he believed that the Government was planning to move against his party. “We strongly reject any suggestion that Hizb ut Tahrir is ‘radicalising’ the Muslim community,” he said. “It is Hizb ut Tahrir who is channelling the emotions of the Muslim community, who have been incensed by the West’s colonialism in the Muslim world, into political work.”

The cleric, who lives in Qatar, has condemned the London bombings, describing them as “black actions”; but he has described insurgents who die fighting American troops in Iraq as martyrs and, according to BBC Monitoring, said in 2003: “Oh God, destroy the usurper Jews, the vile crusaders and infidels.”

The organisers of the conference deny that it is a fudamentalist event. They list Amir Khan, the Olympic medal winning boxer, as one of the guests due to attend.

Shahid Butt, of the Ramadhan Foundation, said that he believed the speakers at the conference would be united in condemning the London bombings. “As Muslims we are totally against all forms of terrorism,” he said. “Islam strictly forbids the killing of all women and children.”

He said the conference was aimed at creating a stronger, more united Muslim community. Mr Butt added: “Sheikh Qaradawi has said that if his health holds up he will attend, but it is dependent on his health. We will not know until a few days before the conference.”

The organisers’ website guestbook carries some criticism of the event for being dominated by fundamentalists. One correspondent has written: “This is the worst kind of fitna [tribulation] in today’s society.”

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