Hizb-ut-Tahrir, which Tony Blair plans to ban as an extremist organisation, had booked Friends Meeting House in Central London using the name Salsa Bill Publishing House.

The group, which describes itself as a non-violent political party seeking to establish an Islamic state, had called a national conference to be attended by 1,000 followers on Sunday. But the Quakers said yesterday that they had cancelled the booking and refunded the fee because they were unhappy that insufficient details and contact information had been provided.

A Quaker spokeswoman said: “We are a pacifist movement and any group which books with us is expected to follow our guidelines.”

A spokesman for Hizb-ut-Tahrir said the conference had been advertised widely but claimed not to know details of the booking. He said: “I don’t deal with the bookings so to be quite honest I don’t have a clue about it.”

It is not clear now where the conference, entitled Hizb-ut-Tahrir and the Vision of the Caliphate, will take place.

In January, Omar Bakri Mohammed, the radical cleric now banned from Britain, held a conference at Friends Meeting House at which 600 people cheered videos of the September 11 atrocities and heard inflammatory speeches. The gathering had been booked as a women’s health conference.

Mr Bakri Mohammed led Hizb-ut-Tahrir in Britain before splitting with the party in 1996 to set up his al-Muhajiroun organisation. He left Britain last month amid fears that he might be arrested, and is living in Lebanon.

Hizb-ut-Tahrir said it hoped that its conference would dispel the image that it was an extremist group.

Hizb-ut-Tahrir’s fee for the hall is believed to have been about £1,500 and speakers would have addressed the audience on the “unholy alliance” between the West and Arab governments and the “role of women in the caliphate”.

The party, which is expected to challenge any attempt to ban it in the courts, held a similar conference at hotel in Central London last month.

Friends House is close to the scene of the July 7 suicide bombings at King’s Cross Underground station and on a No 30 bus route at Tavistock Place.

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