A thousand anti-fascist protesters roared their opposition to the appearance of the two controversial speakers.

Campaigners from Unite Against Fascism, Unison and Jewish student groups gathered outside the Oxford Union, in St Michael's Street, from 6.30pm, carrying placards and loudhailers.

BNP leader Nick Griffin and Holocaust denier David Irving had arrived early to avoid a showdown with the crowd.

Weyman Bennett, of trade union Unite, said: "We're sending a loud message into the Oxford Union that these people should not be given respectability or the platform to deny mass murder and the Holocaust."

Many of the protesters came with banners denouncing the BNP and others covered their faces.

A 25-year-old man, who was wearing a disguise, said: "I'm aware that extremists may collect photos of anti-fascist campaigners and may be targeted, so I don't want to take that risk."

Music, speeches and chants were made at the entrance to the Union, while Respect Party MP George Galloway also turned up. He said: "(David Irving) can have these views, but he should not be given this glamorous platform to expand on it."

The Lord Mayor of Oxford, John Tanner, pictured, said: "The majority of Oxford councillors called on the Union to withdraw the invitation and I am disappointed they have been given a platform to air extreme views."

Some campaigners began climbing on the walls outside the Union, while others chanted: "Ban the BNP" and "Get Fascism off the Streets".

Students Sam Halliday and Rob Morton waved a banner saying Mr Griffin and Mr Irving should be allowed to speak. Mr Halliday said: "I don't agree with what is being said inside, but I think it should be debated in the open, not behind closed doors."

Student rabbi and Oxford Union member David Mitchell said: "It's utterly horrendous. I cannot believe the Oxford Union is giving credibility to these people and I will be resigning my membership in the morning."

Imran Zahid, from Oxford Islamic Society, said: "This is a multi-national country and we should respect everyone's views."