There are concerns that far-right extremists plan to confront al-Muhajiroun, which has not sought a licence from Ken Livingstone to stage the event. Matters are further complicated because a free street opera performance of The Magic Flute is due to take place in Trafalgar Square the same afternoon.
Mr Livingstone said he would take legal action if the rally went ahead, but this is unlikely to deter the group. Two years ago, after a similar illegal rally, he pursued a civil action against one of its leaders but the sole result was a £200 fine. Yesterday one activist said they would happily pay another £200 fine.
Uniformed and undercover officers will be deployed to keep order, but will also monitor the speeches to see if any Race Relations Act offences are committed. A spokesman from Mr Livingstone’s office said: “A letter has been sent to the UK leader of al-Muhajiroun, Anjem Choudary, asking him to confirm that he is not intending to hold a demonstration on the square, but no response has so far been received.
“Following a rally on the square held without permission two years ago, Mr Choudary was successfully prosecuted under the Trafalgar Square bylaws, and the mayor will take a similar approach if the bylaws are again breached.”
Omar Bakri Muhammad, a senior figure in al-Muhajiroun, said his group had not sought a licence because it knew the application would be refused. “I don’t know why Mr Livingstone is so upset. We will be in a public area,” he said. “We are not using the facilities of the square or any of the furniture. Our loudspeakers work on batteries and our banners will be held up by humans.”
He said that even far-right protesters should be allowed on to the square. “They have the right to condemn or agree so long as there is no violence. There is freedom of speech.”
The apparent inability of the authorities to stop al-Muhajiroun holding an event in one of London’s most famous locations has caused widespread disquiet. Its attacks on homosexuality and messages calling on Hindus and Sikhs to convert have also caused anger.
Murad Qureshi, a member of the London assembly and the Metropolitan police authority, said: “This illegal demonstration is the last thing we need for community relations in London at the current time. The views of this fringe organisation are extreme and offensive to other communities, including the vast majority of Muslims living in the capital.”
Arjan Vekaria, security secretary of the Hindu Forum of Britain, accused the authorities of being slow to intervene. “It was only when we informed them that we had received information of vast numbers of Hindus and Sikhs planning to congregate in Trafalgar Square to show their displeasure that the police responded.
“We are not sure if the police understood the gravity and seriousness of the feelings within the community.”
Jack Gilbert, of the Metropolitan police’s lesbian, gay, bisexual and transsexual advisory group, said lessons must be learned. “The Met has made great strides in the way in which individual hate crimes are processed and the way in which victims are supported.
“Nonetheless, had they sought such advice earlier in this case, communities would not have become so concerned.”