POLICE tonight repeated a warning that officers would be out in force around the Oxford Union this evening.

Protests are expected after the Union issued invitations to BNP leader Nick Griffin and Holocaust denier David Irving to speak in a debate on free speech.

A spokesman for Thames Valley Police said: "The debate is a private event with entry by ticket only, and all tickets have been allocated.

"Police will be closely monitoring any issues which may arise nearby and within the community, and there will be a police presence in the area throughout the evening."

Chief Insp Dennis Evernden said: "Our role in this event is to prevent any breach of the peace, facilitate lawful protest and provide reassurance to the general public.

"We are very used to policing protests in Oxford and our aim is to deal with any issues in a professional manner in accordance with the law."

Earlier Oxford MP Evan Harris defended the Oxford Union's controversial decision to invite a convicted Holocaust denier and the leader of the British National Party to speak at the event.

Dr Harris, Liberal Democrat MP for Oxford West and Abingdon, rejected claims that asking David Irving and Nick Griffin to take part in a debate on free speech gave them an undeserved aura of respectability.

The MP, who has himself agreed to take part in tonight's Union debate, told BBC Radio 4's Today programme: "Free speech is not a privilege, it's a right.

"If I want to debate the limits of free speech within the law I can't really do that consistently by no-platforming extremists.

"I don't want a bunch of students telling other students or my constituents or me who I can talk to within the law because that way lies effective despotism."

Dr Harris described the two men as "unpleasant" and their far-right views "wrong" and "horrible".

But he said that no-platform policies led to unwelcome restrictions to free speech. When he was an Oxford University student, in 1986, such a policy led to right-wing Conservative MPs being banned from speaking events, he said.

He added: "It's reasonable within a university for a debate to be had about the limits of free speech."

Tonight's event has been condemned by Oxford East MP Andrew Smith.