Rajapaksa prays in Katunayake, Sri Lanka. (AFP)

London, Dec. 3 (Agencies): A British television channel has broadcast a video of an alleged massacre of blindfolded men and women said to be members or sympathisers of the LTTE.

Colombo dismissed the footage as “unauthentic”.

In the five-minute video, Channel 4 News shows naked prisoners with their hands tied behind their back being shot from behind by soldiers with assault rifles. The killings take place in a field littered with corpses.

According to Channel 4, the footage was actually an extension of another video shown by the channel last year in which soldiers appeared to shoot two blindfolded men.

It said the video was shot shortly before the final triumph of the Sri Lankan army in May 2009.

“The new video seems to show the same incident, but rather than stopping after the execution of a second bound man, it continues and the camera pans left revealing the naked and dead bodies,” the channel said.

Aprestigious debating society in Oxford said it had cancelled a speech by Sri Lanka’s President Mahinda Rajapaksa after planned protests against his visit raised security concerns.

Tamil groups in Britain and their supporters planned a big demonstration in Oxford to coincide with Rajapaksa’s talk at the famous Oxford Union.

The Sri Lankan High Commission in London denied that the Channel 4 video was authentic. “Last year when Channel 4 News telecast a similar video, the government of Sri Lanka clearly established, by reference to technical considerations, that it was not genuine but fake.

“The present video is nothing more than an elongated version of the same video,” it said in a statement.

The High Commission said: “There is a common pattern in these sinister moves. Some sections were replete with photographs of alleged war crimes when Sri Lanka’s application for the extension of GSP facility was being considered by the European Commission.”

A leading British newspaper had received photographs of alleged war crimes when Sri Lankan external affairs minister visited the UK last October.

The latest revelation coincides with the visit to the UK of President Rajapaksa.

Ethnic Tamils had planned to protest against alleged human rights abuses during Sri Lanka’s three-decade war against Tamil separatist rebels, won by the army last year.