Jeremy Corbyn has denied links to a Lebanese extremist who was banned from Britain by the last Labour Government, declaring: "I don't know who this person is".

Dyab Abou Jahjah, an Arab political activist who allegedly fought for Hezbollah and considers "every dead American, British and Dutch soldier a victory," said the Labour leadership front-runner invited him to speak at an anti-Iraq war event in London six years ago.

Yesterday the controversial activist tweeted a picture of the pair sat side-by-side, claiming his "collaboration" with Mr Corbyn was "always guided by common belief in dialogue, justice and equality of all".

In a post on his website today Jahjah reiterated that he had "briefly met and collaborated" with Mr Corbyn in 2009, saying his "openness to dialogue" was what "made the visit possible". In the post he wrote that British soliders in Iraq are a "legitimate target for resistance".

Jahjah has also spoken about "hoax" gas chambers, adding to the list of Holocaust deniers that have been alleged to have links with Mr Corbyn.

But asked on BBC Radio 4's World at One whether reports he had met Jahjah were true, Mr Corbyn replied: "Sorry, who? I saw the name this morning and I asked somebody: 'who is he?' Asked to confirm he had never heard of Jahjah, he said: "I'm sorry, I don't know who this person is."

He again rejected accusations of racism and anti-semitism, describing allegations of links to Holocaust deniers as "deeply offensive". He also moved to clarify why he had described representatives of Hamas and Hezbollah as "friends", saying he used it as "diplomatic language in a meeting".

Labour leadership: The Contenders Show all 4 1 /4 Labour leadership: The Contenders Labour leadership: The Contenders Jeremy Corbyn Jeremy Corbyn started off as the rank outsider in the race to replace Ed Miliband and admitted he was only standing to ensure the left of the party was given a voice in the contest. But the Islington North MP, who first entered Parliament in 1983, is now the firm favourite to be elected Labour leader on September 12 after a surge in left-wing supporters signing up for a vote. PA Labour leadership: The Contenders Liz Kendall Liz Kendall has been labelled the Blairite candidate throughout the contest, which partly explains why she has failed to attract the support needed in a party that has drifted even further from the centre-ground of British politics since the election. She has faced criticism over her relative lack of experience, having only served as an MP since 2010 and having no experience of ministerial or shadow cabinet roles. But that very lack of experience allowed her to initially make a pitch as the only candidate offering real change and a real break from the Blair/Brown/Miliband years, until Jeremy Corbyn entered the race and shifted the whole debate to the left. She is set to finish a disappointing fourth. PA Labour leadership: The Contenders Andy Burnham Andy Burnham started out as the front-runner in the leadership election, seen as the candidate of the left until Jeremy Corbyn entered the race. The former Cabinet minister has found himself squeezed between the growing populism of Corbyn’s radical agenda and the moderate, centre-left Yvette Cooper, not knowing which way to turn. It has attracted damaging labels such as ‘flip-flop Andy’, most notably over his response to the Government’s Welfare Bill. He remains hopeful he can win enough second preference votes to take him over the 50 per cent threshold ahead of Corbyn. PA Labour leadership: The Contenders Yvette Cooper.jpg Yvette Cooper has put her experience and achievements in government at the heart of her offer to the Labour party. She played a key part in setting up Sure Start in Tony Blair’s government and has pledged to continue her record on delivering for young families by promising a “revolution in the way families are supported” by introducing universal free childcare. She has also championed her role as a full-time working mother, taking pride in telling audiences that she does the school run for the kids before her day starts as a politician. But she has been criticised for being too wooden and lacking in passion and her attacks on Liz Kendall for “swallowing the Tory manifesto” at the start of the leadership contest have been criticised for helping Jeremy Corbyn brand all three mainstream candidates as ‘Tory-lite’. PA

"I have met elected representatives of Hamas in Gaza in the company of 60 Members of Parliament from all across Europe," he said. "Does it mean that I consider the policies of Hamas appropriate and ones that I approve [of]? Absolutely of course I don't."

Clarifying his fierce opposition to Holocaust deniers, he said: "My views are that the Holocaust was the most disgraceful and vile process of the history of the 20th century, if not the wider world and that has to be understood by successive generations and it has to be understood by all our children in schools. That surely is important.