Britain's most powerful Islamic body is "in denial" about the prevalence of extreme views among its members, one of its founders has told the BBC.
Sir Iqbal Sacranie's organisation represents 400 groups
The Muslim Council of Britain (MCB) pledged to tackle extremism "head on" after the 7 July attacks in London.
But in a BBC Panorama special, Mehbood Kantharia and other prominent British Muslims question the MCB's commitment to meeting this challenge.
The MCB has branded the programme "deeply unfair" and a "witch-hunt".
Secretary general Sir Iqbal Sacranie said Panorama had used "deliberately garbled quotes in an attempt to malign the Muslim Council of Britain".
He said it had "the barely concealed goal of drawing British Muslims away from being inspired in their political beliefs and actions by the faith of Islam".
"It is unfortunate that just when Britain's 1.6 million Muslims are beginning to make progress in terms of their political participation in the mainstream, there are those who are purposefully trying to sabotage that process," he added.
Mehbood Kantharia was a member of the MCB's central working committee between 1997 and 2004, but has since left the organisation.
He told Panorama: "It is my personal view that because they are in a state of denial they cannot become real, you know, sort of like, forthright, really forthright about wanting to do something about the kind of extremism that prevails."
The MCB, an umbrella organisation of about 400 mosques and other Islamic groups, is seen as representing mainstream Muslim opinion in the UK.
On Saturday the council said Mr Kantharia had informed it that his remarks were not referring to the MCB.
But Mr Kantharia later said that while he had not mentioned the MCB specifically, his comments could have been interpreted as applying to individuals within it.
"I think the MCB is overreacting in this matter," he added.
MCB secretary general Sir Iqbal Sacranie was asked after the 7 July attacks to help set up a task force to root out extremism in Britain's Muslim communities.
After meeting Tony Blair in Downing Street on 19 July he said: "The community is determined to deal with this issue head on."
But an investigation by Panorama reporter John Ware found groups affiliated to the MCB promoting anti-Semitic views, the belief that Islam is a superior ideology to secular British values and the view that Christians and Jews are conspiring to undermine Islam.
In an interview with Mr Ware, Sir Iqbal refused to disown a group known as Al-e-Hadith, which says the ways of Christians and Jews "are based on sick or deviant views" and that "imitating the Kuffar [non-Muslims] leads to a permanent abode in hellfire".
Commenting on the group, Sir Iqbal said "we must accept the reality" of the diversity within the Muslim community in the UK.
He also praised the work of the Islamic Foundation, which promotes the teachings of Jamaa'at Islami founder Sayid Mawdudi.
Mr Mawdudi wrote Islam was a "revolutionary ideology which seeks to alter the social order of the entire world".
In a wide ranging interview, Mr Ware also tackled Sir Iqbal on his decision not to attend the Holocaust Day Memorial and his attendance of a memorial service for Hamas leader Sheikh Ahmed Yassin, who supported suicide bombers in Israel.
Asked what kind of signal his presence at Sheikh Yassin's memorial service sent to young British Muslims, Sir Iqbal said: "If your whole question is based upon one aspect of that person's belief in terms of supporting it, we look into the wider picture. The suicide bombing that you're referring to is one aspect of the whole struggle."
But Sir Iqbal condemned suicide bombings by British Muslims anywhere and said there was no difference between the life of a Palestinian and the life of a Jew and that all life was sacred.
In a separate interview, a senior spokesman for one of the MCB's main affiliates, the Muslim Association of Britain (MAB), appeared to condone the glorification of suicide bombers.
Asked if describing martyrdom in Israel as "divine bliss" meant he was an "apologist for terrorism", Dr Azzam Tamini replied: "If you want to consider me so that's up to you."
London mayor Ken Livingstone earlier this week accused the BBC and other media organisations of conducting a "witch-hunt" against the MCB, which he described as the "mainstream representative body of British Muslims".
The MCB has made a formal complaint to the BBC accusing it of "blatant pro-Israeli bias" and "undermining community relations in the UK".
In his letter of complaint, written before he had viewed the programme, Sir Iqbal said: "It appears the BBC is more interested in furthering a pro-Israeli agenda than assessing the work of Muslim organisations in the UK."
He added: "The BBC should not allow itself to be used by the highly placed supporters of Israel in the British media to make political capital out of the 7 July atrocities in London."
In his response, Panorama editor Mike Robinson, said the programme examined questions "being raised by the Muslim community itself".
"Despite some critical comments to the contrary, it is certainly not the case that nearly all the questioning of Sir Iqbal Sacranie was about Israel."
He added that the BBC "rejects completely any allegation of institutional or programme bias" and he was "confident" the programme would be "a timely contribution to the present debate".
The Panorama special A Question of Leadership is on BBC One at 2220BST on Sunday, 21 August.