Oxford Union calls off appearance by Sri Lanka's President

The Oxford Union has cancelled an address that was to have been delivered tonight by Sri Lanka's President Mahinda Rajapaksa, citing concerns about protests being planned by thousands of demonstrators.

The student debating society said in a statement that following discussions with the local police about the anticipated demonstrations, a decision had been taken that it was not longer practical to proceed with the event.

The plan to disrupt the speech of Mr Rajapaksa came as Tamil activists released new video footage they claimed shows the interrogation of a senior Tamil rebel military commander after he had surrendered to government troops.

The family of the Tamil commander, who went by the name Col Ramesh, say they have had no news of him since he gave himself up to government troops, while the Sri Lankan military reportedly said at the time he had been killed in fighting during the final stages of the war. In the brief video, Col Ramesh is seen answering questions from his captors, apparently Sri Lankan government troops, with a large bandage on his back.

Activists say the new video footage, which has been seen by The Independent, proves he did not die in fighting. They have demanded that the Sri Lankan authorities provide information about him and large numbers of other Liberation Tigers of Tamil Eelam fighters who either surrendered or were captured.

"I last saw my husband on April 18. He called me on May 15 to say he would not be able to telephone again in the foreseeable future," said the commander's wife, Vatsala. Speaking from outside Sri Lanka, she said that she had not seen the video purporting to show the interrogation of her husband, but that news of its existence – if it is genuine – gave her hope he was still alive. Col Ramesh's wife, who has three children, said the commander's niece was with him when he gave himself up to government forces. "He was arrested by the Sri Lankan army," she said.

The final stages of the military operation in the spring of 2009, which destroyed the remnants of the once-lethal rebel forces, were bloody and chaotic. The UN has estimated that 10,000 civilians, holed up in a so-called "no-fire zone", may have been killed as a result of shelling by both sides. Mr Rajapaksa has always rejected demands for an independent inquiry.

The President, who earlier this year was elected to a second term, last month postponed a planned engagement at the Oxford Union. His aides said the postponement was due to his schedule, but reports suggested he was concerned that activists in the UK might seek his arrest, using the same laws that led to the arrest of former Chilean leader General Pinochet.

There was no immediate word from Mr Rajapaksa last night about the cancellation of his address, and the Sri Lankan military was unavailable for comment on the emergence of the video purporting to show the interrogation of Col Ramesh.

Rajiva Wijesinha, a Sri Lankan MP who is also a former secretary of the country's human rights ministry, said inquiries into a number of released videos had suggested they were fake. "There is clearly an interest in making these videos," he said.

Controversial speakers

David Irving

A debate involving the Holocaust denier and historian was cancelled in 2001 after a backlash against his invitation. He appeared six years later, despite widespread public protests.

Nick Griffin

The British National Party leader appeared on the same night as Mr Irving. He was taken into the building by a phalanx of security guards after protests delayed the event.

Kermit the Frog

The appearance by the character from the Muppets in 1994 sparked accusations of dumbing down by the Union. Kermit told the audience: "Frogs usually only get in here by being in an experiment."