The BBC is facing a High Court challenge over its decision to censor a party political broadcast in the run-up to Thursday’s local elections.

A Christian party has begun legal action after the corporation insisted on changes to a short film in which the party voiced opposition to the building of Europe’s biggest mosque next to the site of the 2012 Olympics.

Tablighi Jamaat, the Islamic missionary group behind the £75 million Abbey Mills mosque, opposes inter-faith dialogue and preaches that non-Muslims are an evil and corrupting influence. One of its British advocates has said that it aims to rescue Muslims from the culture and civilisation of Jews and Christians by creating “such hatred for their ways as human beings have for urine and excreta”.

The Christian Choice election broadcast would have described Tablighi Jamaat as “a separatist Islamic group” before welcoming that some “moderate Muslims” were opposed to the mosque complex.

Alan Craig, the party’s candidate in the London mayoral election, also on Thursday, said that he was forced to change the wording at the insistence of lawyers at the BBC and ITV, which will also feature in the court action.

The BBC refused to accept “separatist” — the corporation asked for “controversial” instead — and barred the use of “moderate Muslims” because the phrase implied that Tablighi Jamaat was less than moderate.

ITV went a step farther, demanding that the adjective “controversial” be used merely to describe the planned mosque and not the group itself.

Mr Craig, a councillor in Newham, East London, the site of the proposed development, said that his party reluctantly agreed to a watered-down version that was acceptable to the BBC and ITV. The amended five-minute film was aired in the London area on Wednesday last week, but papers will be lodged in the High Court today to seek a judicial review of the broadcasters’ actions. If the action succeeds, Mr Craig hopes that the televison companies will be forced to screen his original film before voters go to the polls.

“This was a politically correct attempt to close down reasoned discussion and debate. It’s a matter of freedom of speech and democracy,” he said. “People rub along fairly well together in the East End of London, all different communities, faiths, colours and nationalities, but Tablighi Jamaat have been antagonistic separatists since they were founded.”

Tablighi Jamaat was founded in India in 1926. It is closely linked to the ultra-conservative Deobandi school of thought, which gave birth to the Taleban in Afghanistan and is becoming increasingly powerful in Britain.

Its leaders claim millions of adherents worldwide and insist that the secretive Sunni group — which has traditionally shunned all publicity — is peaceful and apolitical. A spokesman for the Abbey Mills project said last night that Tablighi Jamaat was an open organisation that preached neither separatism nor extremism. International intelligence agencies, however, say that the revivalist movement has acted, in some instances, as a gateway to terrorism. Adherents have been linked to atrocities, including the 7/7 suicide attack on London.

More than 2,500 Muslims have signed a petition against the project and its opponents include Irfan alAlawi, the international director of the Centre for Islamic Pluralism, and Dr Ghayasuddin Siddiqui, who co-founded the Muslim Parliament of Britain.

Taj Hargey, chairman of the Muslim Educational Centre of Oxford, said that the proposed mosque would become “the headquarters for radical . . . sectarianism in the UK”. He accused Tablighi Jamaat of preaching “a virulent, intolerant version of Islam”.

Neither the BBC nor ITV would discuss its specific concerns.

Faisal Iqbal, 25, a member of Tablighi Jamaat who is also an IT consultant and part of the Abbey Mills project team, said last night that it was wrong to suggest that the movement had a separatist agenda. “When comments by some Tablighi Jamaat supporters are read out of context they may seem to be separatist, but what we’re trying to discuss is distancing ourselves from beliefs which move us away from belief in God and which take us into things we consider to be a sin,” he said. “Stopping all interaction with people who are non-Muslims has never been a doctrine of Islam. Our religion says we must treat our neighbours with the highest regard, regardless of their religion.”

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