Al-Awlaki has been accused by US counter terrorism officials and the Yemeni government of being one of the driving forces behind Umar Farouk Abdulmutallab's conversion to an extreme form of Islam.
Today we can reveal al-Awlaki has spoken on at least seven occasions at five different venues around Britain via video-link in the last three years alone, despite being banned from entering this country in 2006.
On at least two occasions the American-born cleric addressed audiences at a Muslim centre which was receiving taxpayers money under Government's programme to prevent violent extremism.
Al-Awlaki is one of a series of radical preachers who have spoken at venues benefiting from money intended to counter Islamist radicalisation.
Critics have condemned the ease with which al-Awlaki – described by the US Government as the spiritual leader of the 9/11 bombers – has been able to spread his message of hate and division in this country.
Al-Awlaki, who is also thought to have influenced Major Nidal Malik Hasan, the US soldier who killed 13 people at a military base in Texas in November, has been accused by the US Department of Homeland Security of using his video lectures to "encourage terrorist attacks".
The 38-year-old's extremist ideology is laid bare in his pamphlet '44 Ways to Support Jihad' in which he declares: "The hatred of kuffar [non-Muslims] is a central element of our military creed" and "arms training is an essential part of preparation for Jihad".
His role in influencing Abdulmutallab, who is suspected of attempting to blow up a flight to Detroit on Christmas Day, has only become apparent in the past 48 hours.
Abdulmutallab, who moved to the Yemen in August 2009 after completing an engineering degree at University College London, has told the FBI he made contact with al-Qaeda through a preacher he met over the internet. This man is now thought to be al-Awlaki, who himself moved to the Yemen after leaving Britain in 2004.
Yemen's deputy prime minister for defence and security affairs, Rashad Mohammed al-Alimi, said on Friday that investigators now believe Abdulmutallab met al-Qaeda operatives in a house built by al-Awlaki to hold theological sessions and where he had previously met Abdulmutallab.
It had been thought the extremist cleric had been killed in a Christmas Eve air strike on the house, in the southeastern Yemen province of Shabwa, but Mr al-Alimi said he is believed to be still alive.
Al-Awlaki's influence on Abdulmutallab is understood to have begun during the bomber's time as a student in London between September 2005 and the end of 2008. He is thought to have attended at least one of a number of video-link lectures given by al-Awlaki at the East London Mosque's London Muslim Centre (LMC), in Whitechapel, during this period.
Despite the LMC receiving at least £60,000 in funding from the Government's Preventing Violent Extremism Fund (PVEF) in the past two years, al-Awlaki has during that period been allowed to address at least two gatherings at the venue via video-link, including one on New Year's Day last year called The End of Time and advertised with a poster showing the destruction of New York.
His appearances at the LMC were just part of an extensive 'video tour' by al-Awlaki of venues around the country.
From the LMC he went on to address an audience via video-link at a taxpayer-funded arts centre in East London in April, after Tower Hamlets council gave its approval for the meeting to go ahead.
Since 2007 he has given similar video-link sermons to worshippers at the Al Huda Mosque in Bradford, to Islamic student societies at the University of Westminster and at an event staged by the Cageprisoners organisation in September 2008 at the Wandsworth Civic Suite, in south London.
The true picture of the continued influence of Islamist extremism at British campuses has begun to emerge since the arrest of Abdulmutallab, who headed University College London's Islamic Society between 2006-2007.
He is the fourth president of a university Islamic society to face terror charges in the past three years and Whitehall sources have confirmed that MI5 is now investigating his possible links with other radical individuals at UCL and with other Islamic student societies.
During his presidency, Muslim students at UCL tried to water down the student union rules on anti-semitism by including Islamophobia in its definition. The university's Jewish society was forced to launch a campaign to stop the motion in February 2007.
Over the same period Abdulmutallab organised a series of events featuring a number of Islamic radicals. This newspaper can now disclose new details of controversial Muslim speakers who have been invited to address events organised by UCL Isoc – raising concerns of whether university authorities have taken sufficient measures to prevent violent extremism on campus.
Murtaza Khan, who was filmed in a television documentary delivering a diatribe against Jews, Christians and "filthy non-Muslim doctors", was invited to speak at an event held on university premises in December 2007.
Abu Usamah, an extremist cleric born in the US, was invited to speak at the same event and an internet video "scrapbook" of the event features a recording of his voice. The preacher has suggested that homosexuals and opponents of Islam should be killed.
When Abu Usamah was again invited to appear at UCL last year, concerns led to him being barred by the university authorities.
Several other events planned for last year were only cancelled after pressure from campaign groups such as the Centre for Social Cohesion, including an appearance by Abu Usama Adh Dhahabee, a hard-line preacher who advocates holy war and hatred against non-Muslims.
Abu Dhahabee did, however, speak at an event organised by the Islamic society at another institution, the University of East London, last June.
Disturbingly, hard-line preachers continue to address audiences at mosques that have received funding, training or advice under the prevention strategy launched by ministers to stop people turning to violent extremism, raising fears that the seeds are being sown for more would-be suicide bombers like Abdulmutallab.
Two ultraconservative preachers last week addressed audiences at the Green Lane Mosque in Birmingham
The mosque has taken part in leadership and mentoring programmes for imams and officials organised by Birmingham City Council, to help prevent extremists infiltrating the city's mosques. These projects have received £161,000 from the PVEF over the past three years. Teachers at its madrassa have also attended courses paid for by £54,000 of PVE funding.
Despite this, the Kuwaiti cleric, Sheikh Faisal al-Jassim, was invited to address a conference at the mosque on Christmas and Boxing Day, along with fellow radical preacher Abdul Aziz As-Sadhan. Both belong to the hard-line Wahhabi branch of Islam followed by al-Qaeda's leaders and supporters.
According to the anti-extremism think-tank, Quilliam, Al-Jassim has previously called for Muslims to take up the banner of Jihad against the "enemies of Islam", stating: "If people returned to that the banner of jihad would be lifted to raise the word of Allah and to implement his Shariah. We have to also prepare all the weapons we can and prepare the material and moral means, so when these things are achieved Allah will help us to victory."
Quilliam says that As-Sadhan stated in a sermon last January: "Jews (may Allah make them ugly) have smeared creation and defaced mankind. History testifies that the band of Jews were responsible for every disorder and fierce war."
In a statement the mosque said: "Green Lane Masjid and Community Centre is fully aware of the responsibilities it has towards the diverse communities it serves. It has various policies and controls in place to ensure it fulfils its aims and objectives in a responsible manner and that it complies with the law including the Racial and Religious Hatred Act 2006.
"Neither of the speakers condone disseminating divisive and destructive message, nor do they consider it permissible to break the law of the land. Green Lane Masjid and Community Centre has always condemned incitement to terrorism, extremism, racism and intolerance."
Another hard-line conservative preacher, Houston-based Yasir Qadhi – who has admitted meeting Abdulmutallab in the Texan city in August 2008 – spoke at a meeting held on New Year's Day at the London Muslim Centre.
In 2001, Qadhi described the holocaust as a hoax, claiming that "Hitler never intended to mass-destroy the Jews" and "All this [the Holocaust] is false propaganda". Although he later claimed he had been misled into making these statements, according to the Centre for Social Cohesion he more recently posted links to articles by a notorious Holocaust denier on an Islamic online forum.
Also speaking at Friday's conference – titled Dark Forces: The Enemy Within – was Hamza Andreas Tzortzis, a convert of Greek origin, who denounced attempts to reform Islam as motivated by failed notions of western liberal, secular democracy
Tzortzis, who speaks regularly at universities throughout the country, including UCL, Queen Mary in London and Bath, has previously stated: "We as Muslims reject the idea of freedom of speech, and even the idea of freedom."
Dilowar Khan, Director of the LMC, defended the decision to host Mr Qadhi and Mr Tzortzis. He said: "From the information we have there is no evidence to suggest that either of the speakers hold any extremist views. We do not believe there to be any contradiction between their appearance and the Centre's participation in the Government's Preventing Violent Extremism Strategy.
"As far as we are aware Mr Qadhi has said he was misled to take a position on the Holocaust which he later retracted."
He added that al-Awlaki would no longer be allowed to address audiences on its premises.
But Houriya Ahmed, of the Centre for Social Cohesion, said: "We have repeatedly warned that academic institutions and mosques are hotbeds of Islamist radicalisation. It is time university authorities, mosques and relevant government bodies take on greater responsibility for the extremism that takes place in their own backyards."
Quilliam stated: "The majority of British Muslims will find this hatemongering despicable. The principle of taking up arms in order to impose a single religious interpretation on others is at the core of al-Qaeda's jihadist ideology. British Muslims do not need al-Qaeda's fellow-travellers lecturing us on history, politics or religion in British mosques."