A controversial Oxford Union debate involving the BNP's leader and a Holocaust denier could be cancelled.

Historian David Irving, jailed in Austria for denying the Nazi execution of millions of Jews and British National Party leader Nick Griffin have both been invited to the Union's Free Speech Forum on Monday.

The invitation of the two men to speak at the Union has caused such a storm of protest that a rally has been planned in Oxford tonight and Defence Secretary Des Browne will boycott another debate he was invited to.

But last night Union president Luke Tryl said it would be put to members of the Union to vote on the issue on Friday A spokesman for the BNP said it was disappointed to hear the event might be cancelled. Mr Irving was unavailable for comment.

Mr Tryl said: "I want the final decision to be with the members of the society, and if they decide that we shouldn't invite Nick Griffin and David Irving, then I will cancel the whole event."

Mr Irving was arrested in 2005 by Austrian police for glorifying and identifying with the Nazis, and denying the Holocaust in a speech he made in Austria in 1989. He admitted the crime of holocaust denial and was imprisoned from February to December 2006, but released after an appeal.

Mr Griffin became the leader of the BNP in 1999.

Campaigners will be at Oxford's Town Hall, in St Aldate's, tonight, calling on the Oxford Union to retract the invitations. Unite Against Fascism has organised the rally in conjunction with Oxford University Students' Union.

Martin McCluskey, president of Oxford University Students' Union, said: "First and foremost, Oxford University Students' Union has been concerned about the safety of students and local residents of Oxford.

"We have made it clear we support freedom of speech and any genuine debate on it. Where the BNP and Holocaust deniers go, violence follows."

However, Raghib Ali, one of the founders of the Oxford Islam and Muslim Awareness Project, said there were dangers in depriving the two men of a platform.

Dr Ali, who is attending the rally tonight, said: "The views these men hold are dangerous and lead to further prejudice. But by not giving them a platform you push them underground and make them more dangerous."

Various speakers who were due to take part in debates at the Union are boycotting speaking engagements. These include television presenter June Sarpong, Labour MP Austin Mitchell and the Defence Secretary, Des Browne.