Inside East London Mosque yesterday afternoon, an elderly and pale imam with a thick grey beard addressed a wedding congregation on the importance of individual responsibility.
"Those who follow Islam follow a lonely path," he told hundreds of guests in a frail voice. "But everyone is responsible for what he does. On the day of Judgement each person will come alone to Allah."
The speech was part of a "nasiha", a sermon of advice to a new groom as he embarks on married life. But the imam's words had a wider resonance.
Umar Farouk Abdulmutallab, the young Nigerian accused of trying to blow up an American airliner on Christmas Day, visited East London Mosque in Whitechapel at least three times when he was a student studying at University College London – he graduated last June. He is thought to have already turned to fundamentalism during his schooling.
MI5 and Special Branch are searching through intelligence for where and when Abdulmutallab became set on his path towards violent fundamentalism. For worshippers at the mosque, the fear is that they are being judged as a community for the actions of one man.
"It's the implication that worries me," said Hussain Shefaar, a local primary school teacher and one of the mosque's trustees. "For all we know he came in a few times to pray because he was in the area at prayer time."
Built by Bangladeshi and Pakistani families that settled in London's East End during the 1960s and 1970s, the mosque has become one of the country's largest and most prominent Islamic institutions. Its congregation is as ethnically varied as the East End itself; more than 20,000 people every week attend prayers, family classes, lectures, weddings and even the mosque's fitness centre. Elderly first-generation Bengalis in traditional tunics worship alongside newer migrants from Afghanistan, Somalia and North Africa.
The mosque regularly issues statements condemning jihadism and long ago barred firebrand preachers such as Al Muhajiroun's Omar Bakri Muhammad and Anjem Choudhary. The trustees point to an £8m family centre under construction which will double the prayer spaces for women as testament to their liberal and inclusive leanings. They maintain that it is important to have an "open door" policy which allows in Muslims from all walks of life.
But it is this open door policy that has led critics to accuse the mosque of being soft on fundamentalist preachers. On New Year's Day 2009, for instance, a group unaffiliated with the mosque called Noor Pro Media hired a room inside the London Muslim Centre (the conference hall attached to the mosque) for an afternoon of lectures. One video lecture was given by an American-born, Yemen-based preacher called Anwar al-Awlaki, a rabble-rousing cleric with links to al-Qa'ida who has become a popular online sheikh for English-speaking jihadists.
The event went largely unnoticed until this November, when Major Nidal Malik Hasan, a US army medic, went on a gun rampage on a military base in Fort Hood Texas. Investigators later learnt that Hasan had been in regular communication with al-Awlaki. Abdulmutallab was also in contact with al-Awlaki.
East London Mosque maintained that it was not told that Noor Pro Media had invited al-Awlaki to speak and would not have allowed it. But there has been no move to forbid those who invited him from using the mosque's facilities again.
For New Year's Day, Noor Pro Media has hired a room in the London Muslim Centre and has another series of lectures planned. While there is no suggestion that al-Awlaki will appear by video (the Yemeni government claims to have killed him last week in an airstrike), those due to speak include Yassir Qadhi, a Saudi-trained preacher who has given a series of anti-Shia and anti-Semitic lectures.
Abdullah Faliq, another mosque trustee, said: "What people fail to remember is that we have been tackling extremism since the mid-1990s and we will continue to do so."
Azam Hasan, a 45-year-old trader who lives locally and attended prayers yesterday afternoon, was philosophical. "In a few weeks time the hype will die down. But think of the damage that is done to the community around here. All it takes is for a guy to come to our mosque a few times when he was a student and we're suddenly suspect. What he [Abdulmutallab] tried to do was unforgivable and none of us here would support this kind of thing. Make sure people know that."