DETECTIVES were today trying to find out why two bombs found at an Oxford college on Monday did not explode.

Police refused to talk about the construction of the two incendiary devices discovered underneath a temporary building at Templeton College in Kennington.

But a spokesman said: "The devices look viable and the exact reason they did not ignite will form part of the forensic examination."

The bombs were discovered after Oxford University security staff saw a posting on the Animal Liberation Front's website - Biteback - on Sunday.

Police have still not confirmed that the ALF was behind the attack but have simply said that animal rights is a strong line of enquiry.

The spokesman said: "Although it has been claimed, this is just the word of someone on a website. It is hardly conclusive evidence."

Operation Rumble was established to monitor and investigate attacks against Oxford University by animal rights extremists and a spokesman said the site was regularly monitored.

Spokesman for non-violent animal rights protest group Speak, Mel Broughton, refused to condemn the attacks, but said: "As a general observation I am far more concerned about the violence and suffering to animals than to the property of Oxford University.

"I am always concerned about violence to life but I have consistently said I won't be drawn into condemning or condoning action outside the Speak zone."

All items seized at the scene have been sent away for through testing at a forensic laboratory.

The police spokesman added: "We would ask members of the public; particularly those who are part of the University community, to remain vigilant, to report any suspicious activity and to pass on any information which could assist the inquiry team to the Police Enquiry Centre on 08458 505505.

A spokesman for the University said: "Our advice remains the same, that all members of the University should be vigilant and report anything suspicious to the University's security team or the police, but that members of the University should not be deterred from going about their usual activities."