Sadiq Khan, Labour's candidate for London mayor, supported groups promoting Islamic extremism and gave a speech while the 'black flag of jihad' was openly flying, MailOnline can reveal.

In a series of incidents between 2008 and 2012, Mr Khan promoted organisations that have advocated violence against women, been accused in Parliament of spreading anti-Semitism and homophobia, and staged events featuring extremists and terrorists.

The revelations will come as a major embarrassment for the mayoral hopeful, who has spoken publicly of his concerns that his own daughter will become an extremist.

Islamic: Mr Khan praised the Islamic model of finance, which prohibits charging interest and investing in the alcohol and pig farming industries, and went on to denounce terrorism

Radical: A youth holds up the 'black flag of global jihad' in the audience during Mr Khan's speech

Support: Sadiq Khan MP gives a speech at the Global Peace and Unity conference in 2008, an event organised by the controversial Islam Channel, which has been censured repeatedly by Ofcom for extremism

Taliban: A woman waves what appears to be a white version of the flag, often associated with the Taliban

THE 'BLACK FLAG OF JIHAD' Fanatic: Umar Islam, who is accused of plotting to blow up a passenger jet over the Atlantic, delivers a video message in front of the 'black flag of jihad' The use of a black flag with white holy script is an ancient tradition in the Islamic world. According to the Quilliam Foundation, some believe that one of Mohammed's original banners, the Uqab, was black. In the modern era, however, black flags with the Islamic declaration of faith have become popular with Jihadist and Islamist groups. Al-Qaeda, al-Shabab, Boko Haram, Jabhat al-Nusra, al-Tawhid wal-Jihad in Iraq, Jihadist fighters in Chechnya, Hizb al-Tahrir and ISIS have all adopted versions of the flag. The Arabic writing on the banner is usually the basic Islamic declarations of faith, known as the 'shahadas'. All these groups occasionally reverse these colours. A black flag, 'al-rāya', for war; a white flag, 'al-liwa’, for peace. The white version was particularly adopted by the Taliban in Afghanistan for peacetime. The black version is supposedly the flag of the 'Muslim army', and has been referred to as the 'flag of jihad'. According to Kamal Alam, Research Analyst at the Royal United Services Institute (RUSI), the flag is 'the best known symbol of global jihad', and is 'instantly recognisable as Al Qaeda and other groups'. 'It is the regular flag used by all groups calling for a global Caliphate,' he told MailOnline. Advertisement

It follows the news that Mr Khan's former brother-in-law, Makbool Javaid, preached hatred against non-Muslims at a rally in Trafalgar Square – with the 'black flag of jihad' flying behind him.

Mr Khan was filmed delivering a speech at the Global Peace and Unity festival in 2008 organised by the Islam Channel, which Ofcom found guilty of extremism both before and after the MP's appearance.

During Mr Khan's address, members of the audience were seen proudly flying the 'flag of global jihad'.

One boy, who is also apparently wearing a jihadi headband, can be seen brandishing the flag at the camera and grinning.

The flag, displaying white Arabic script on a black background, is used by extremist groups including Al Qaeda and Boko Haram.

A spokesman for Mr Khan said that the banner was simply 'a black flag with the Islamic statement of faith on it', and that he was 'not sure what the jihadi context [was]'.

However, a number of independent experts have confirmed to MailOnline that the flag is a recognised emblem of militant Islam.

'It is definitely equated with global terrorism, for sure,' said Kamal Alam, Research Analyst at the Royal United Services Institute (RUSI).

'It is totally shocking for a senior Labour MP to give a speech while that flag is being flown and nobody is challenging it.'

According to Usama Hasan, a former jihadist now at the Quilliam Foundation think tank, the flag was originally widely used but 'its significance has changed over the centuries' to become associated with extremism.

Dr Elizabeth Kendall, Senior Research Fellow in Arabic at Pembroke College, Oxford, co-editor of Twenty-First Century Jihad, and one of Britain's foremost experts in radical Islam, agrees.

'Anyone who is using this flag today must be aware of its contemporary links to militant jihadist groups,' she told MailOnline.

'It has become a very potent symbol. It suggests that there is a radical Islamic worldview represented.

'If I were an MP giving a speech and this was in the crowd, I'd definitely want my security detail to investigate.'

The footage shows the flag flying openly during the MP's speech, without complaint from any other member of the audience, the organisers, or Mr Khan himself.

During his address, the Tooting MP spoke frequently in Arabic and praised Islamic finance, which forbids investing in 'haram' industries like alcohol production and pig farming, as well as charging interest.

Anyone who is using this flag today must be aware of its contemporary links to militant jihadist groups Dr Elizabeth Kendall, jihadism expert, Senior Research Fellow in Arabic at Pembroke College, Oxford

'Suddenly, Islamic finance isn’t such a bad thing [following the global financial crash],' he said.

This will raise concerns about Mr Khan's intentions for the City of London if he is elected Mayor.

Mr Khan's speech was organised by the Islam Channel, a controversial Muslim satellite station that has been repeatedly penalised by Ofcom for promoting extremist ideals such as marital rape.

In one incident highlighted by Ofcom, Islam Channel presenter Nazreen Nawaz said: 'it shouldn't be such a big problem where the man feels he has to force himself upon the woman'.

The Mayoral hopeful has spoken at the annual event at least four times.

In his address, Mr Khan said: 'Congratulations to the team at Islam Channel for another record-breaking year. Let's hear it for Islam Channel!'

During the year to which the Tooting MP referred, Ofcom had fined the station £30,000 for a series of misdemeanours, including a lack of objectivity on Israel.

Moreover, l ess than two weeks after Mr Khan's speech, the station was again censured by the regulator for advocating marital rape and violence against women, and describing those who wear perfume as 'prostitutes'.

The high-profile Ofcom investigation was well underway when Mr Khan delivered his speech.

The unchallenged presence of a jihadi flag at the event – together with the Islam Channel's history of radicalism and censure by Ofcom – raises troubling questions about Mr Khan's judgement.

The Islam Channel has not responded to MailOnline's repeated requests for comment. But it is not the only controversial group with which Mr Khan has been associated.

Fanatic: 'Jihadi Sid' holds up another jihadi flag in a Channel 4 documentary 'The Jihadis Next Door'

In June 2012, the Labour MP gave a speech at the opening of a conference held by the Federation of Student Islamic Societies (FOSIS), which has run gender-segregated events at universities and has been repeatedly accused of campus extremism.

FOSIS is an umbrella organisation for Islamic student groups, a number of which have welcomed hate preachers onto university campuses.

Last month, a Daily Mail investigation revealed a 'campaign of hate' on campuses which is 'poisoning the minds of students'.

It is totally shocking for a senior Labour MP to give a speech while that flag is being flown and nobody is challenging it Kamal Alam, Research Analyst at the Royal United Services Institute (RUSI)

In addition to Mr Khan, speakers at FOSIS events have included:

FOSIS has been condemned by Theresa May, the Home Secretary, for its failure to 'fully challenge terrorist and extremist ideology'.

A Prevent report produced by the Government the year before Mr Khan's speech said:

'There are several examples of students engaging in terrorism or related activities while members of university societies affiliated to FOSIS.

'Such extremists must have no part in any organisation that wishes to be recognised as a representative body.'

On his personal website, Mr Khan highlights the fact that in 2012, he received an 'Achievement and Inspiration' award from FOSIS.

The MP lent his support to yet another controversial organisation during the same period. Known as iEngage or Engage, it has since been rebranded as Muslim Engagement and Development (Mend).

It was described in Parliament by Robert Halfon, a Conserative MP, as 'aggressively anti-Semitic, homophobic and [with] extensive links to terrorism in Tunisia and the Middle East'.

Proud: A screenshot of Sadiq Khan's website in which he publicises an award he received from FOSIS

Extremists: Haitham Al-Haddad, left, called Jews 'the descendants of apes and pigs', and Anwar al-Awlaki, right, an al-Qaeda recruiter killed by a US drone strike in 2011. Both have been linked to FOSIS

Hate: CAGE director Moazzam Begg, left, and Azzam Tamimi, right, a Palestinian academic who has said he would carry out a suicide attack himself. Both have been linked to FOSIS

Appearance: Sadiq Khan MP gives a speech at a FOSIS event. The group's logo can be seen behind him

In 2011, there was an effort to bar the group from involvement with the All Party Parliamentary Group on Islamophobia, on account of its links to extremism.

Mr Khan led the Labour MPs who argued that it should not be banned. Their efforts were initially successful.

Four months later, iEngage's chief executive wrote to the Home Secretary asking her to lift a ban on the extremist preacher Zakir Naik, who stated that 'every Muslim should be a terrorist'.

London is one of the world's biggest targets for terrorists. If Mr Khan is not going to stand up to jihadism, he shouldn't be Mayor Davis Lewin, Deputy Director and Head of Policy and Research at the Henry Jackson Society

The group was removed from Parliament the following month.

The organisation has produced a video featuring the preacher Haitham al-Haddad, who claimed that 'I received so many requests from Western women who committed adultery and they were begging me if they can find a way to a Muslim country to be stoned to death'.

A fundraising dinner for Mend featured the firebrand preacher Abu Eesa Niamatullah, who stated in an essay posted online that 'women should not be in the workplace whatsoever, full stop,' and that carrying banknotes is inadvisable as 'the Queen’s crown isn’t a suitable hijab'.

Azad Ali, who once wrote a blog quoting an Islamic militant who justified the killing of British soldiers, and who attended many of Abu Qatada's sermons, is Mend's longstanding Director of Engagement.

Mr Khan's sympathy for the group, in addition to his links to FOSIS and the Islam Channel, will cause outrage among backbenchers on both sides of the House.

'Khan is Jeremy Corbyn's man in London, and Jeremy Corbyn was Khan's man during the Labour leadership campaign,' said Steve Brine MP, the Conservative representative for Winchester.

'Nobody will be surprised at this. When it comes to his fitness to be London mayor, people can draw their own conclusions.'

A Mend spokesman said: 'In February 2011, after his cowardly abuse of Absolute Privilege, Engage challenged Mr Halfon to repeat his defamatory claims outside Parliament.

'He has never substantiated his allegations nor since repeated them in circumstances where he would be forced to corroborate his libellous claims.

'Mend enjoys a good working relationship with MPs on the newly constituted all party parliamentary group on Islamophobia and we continue to support its important work on tackling anti-Muslim hostility and hatred, including in sections of the British press.'

Davis Lewin, Deputy Director and Head of Policy and Research at the Henry Jackson Society think-tank, said:

'London is one of the world's biggest targets for terrorists. If Mr Khan is not going to stand up to jihadism, he shouldn't be Mayor.'

When contacted by MailOnline, a spokesman for Mr Khan said: 'Senior Government and Conservative figures, including David Cameron, Boris Johnson and Lynton Crosby, have spoken at events organised by each of these organisations more recently than Sadiq.

'Sadiq has consistently called for more to be done to tackle extremism and radicalisation – and outlined detailed plans to do so as Mayor.'