Jeremy Corbyn addressed a rally attended by 300 members of an extremist group linked to the leader of the London Bridge attacks.

He addressed an anti-Israel protest where Islamists from Al Muhajiroun chanted about their support for Osama Bin Laden and shouted slogans calling for Israelis to be gassed. Two were dressed in mock suicide bomber outfits.

Khuram Butt, one of the three Borough Market murderers, was a supporter of Al Muhajiroun and an associate of its leader Anjem Choudary, the jailed hate preacher.

It was also claimed yesterday that the security services are looking into a second attacker’s links to the preacher.

The now-Labour leader addressed an anti-Israel protest where Islamists from Al Muhajiroun chanted about their support for Osama Bin Laden and shouted slogans calling for Israelis to be gassed

Omar Bakri Muhammad (left), the leader of al Muhajiroun, is pictured addressing a rally in Trafalgar Square in 2002 alongside hate preacher Abu Hamza. Bakri fled the UK shortly after the 2005 London bombings and is on the run in Lebanon while Hamza is serving life behind bars in the United States for terrorism offences

Details of Mr Corbyn’s attendance at the infamous demonstration in May 2002 are a blow to the Labour leader just 24 hours before the polls open.

The Mail can also reveal that he and his shadow chancellor John McDonnell both voted against the counter-terrorism law used to ban Al Muhajiroun and criminalise its members and leaders.

Jeremy Corbyn, pictured on Sunday in Carlisle, addressed a rally in 2002 which was attended by members of the now banned terror group al Muhajiroun

Defence Secretary Michael Fallon claimed the revelations showed Mr Corbyn could not be trusted with power. He said: ‘Jeremy Corbyn wants to be prime minister in just two days, but this latest revelation about his association with extremists shows exactly why he is unfit to lead the country.

‘He has a long track record of siding with people who want to damage and attack the UK and there can be no excuse for his decision to address this rally.

‘There is a very real risk that Jeremy Corbyn and his Shadow Home Secretary Diane Abbott will be in charge of our security and borders on Friday unless people vote for Theresa May and her Conservative team.’

A spokesman for Mr Corbyn said: ‘Jeremy addressed a broad-based rally in support of Palestinian rights. It was a public event and he was in no way responsible for the views of all of the thousands of attendees. Jeremy condemns Al Muhajiroun in the strongest possible terms.’

But the Labour leader has been exposed for calling terrorist groups Hezbollah and Hamas his friends, describing the death of Bin Laden as a tragedy, boasting of opposing anti-terror legislation in his 30-year career as an MP, and opposing powers stopping would-be terrorists travelling to fight with Islamic State.

Details of the demonstration were found on the communist Weekly Worker website. It described the ‘ultra- reactionaries’ of Al Muhajiroun chanting ‘Skud, Skud Israel’ and ‘Gas, gas Tel Aviv’ , along with declarations of support for Al Qaeda.

Khuram Butt, pictured on the Channel 4 documentary The Jihadis Next Door, was linked to the terror group al Muhajiroun. He and two other terrorists killed seven people and injured dozens more in the London Bridge terror attack

Anjem Choudary, pictured at a rally outside Regent's Park mosque in 2015, was one of the ringleaders behind the now banned terror group al Muhajiroun. He is currently in jail for encouraging his supporters to join the terror group ISISin a series of lectures on YouTube

It added: ‘Two would-be suicide posers were dressed in combat fatigues with a “bomb” strapped to their waists. This section accounted for no more than 200-300, but they made a noise far out of proportion to their numbers.’

Mr Corbyn, then a backbench Labour MP, also addressed the rally, which police estimated was attended by around 8,000 people.

He made a speech in which he called for Israeli leader Ariel Sharon to be put on trial at the International Criminal Court and called for an end to trade with Israel.

‘Too many people have suffered for to long, too many young people have died as a result of this illegal occupation,’ he said.

Al Muhajiroun was set up by hate preacher Omar Bakri Mohammad, and sparked outrage when it described the 9/11 hijackers as the ‘Magnificent 19’.

Sadiq Khan stands with paramedics this morning to hold a minute's silence for those killed in the London Bridge terror attack. Seven were killed and dozens injured in the carnage

Mourners remember those killed in the terror attack at the floral tribute in London Bridge

He was exiled from the UK in 2005 in the wake of the July 7 terror attacks when leadership of the group passed to Choudary.

Yesterday the Mail revealed Butt joined Choudary on College Green outside the Palace of Westminster the day after the murder of Fusilier Lee Rigby. He verbally assaulted a moderate Muslim leader who had taken exception to Choudary’s extreme rhetoric including the remark that one of the killers, Michael Adebolajo, was a ‘practising Muslim and a family man who he was proud of’.

In 2000 Mr Corbyn and John McDonnell voted against Labour’s Terrorism Act that made membership of proscribed groups a criminal offence. Al Muhajiroun was added to the list in 2010.