Sri Lanka's President Rajapakse Oxford Union visit has been cancelled over "security concerns". Channel 4 News last night revealed new footage of an alleged massacre of Tamil prisoners in Sri Lanka.

Sri Lanka's President Mahinda Rajapakse cancels his visit to Oxford amid security concerns (Reuters).

President Mahinda Rajapakse was due to speak on Thursday at the Oxford Union.

However, the Union issued a statement today cancelling his visit "due to security concerns".

"Due to security concerns surrounding Mr Rajapakse's visit which have recently been brought to our attention by the police, the Union has regretfully found that the talk is no longer practicable and has had to cancel his address," the statement read.

The Union added that it maintained a "politically neutral stance" regarding speakers, stressing that "the decision was not made in relation to any aspect of Mr Rajapakse's political position, the policies of his administration or any allegations against his government."

Instead, the talk was cancelled because "due to the sheer scale of the expected protests, we do not feel that the talk can reasonably and safely go ahead as planned."

Mr Rajapakse has already met with Defence Secretary Liam Fox today in a "private capacity", the Defence Secretary's spokesman told Channel 4 News. He declined to comment further on the meeting.

Allegations

A UN panel is currently investigating alleged violations of international law towards the end of the 26-year Sri Lanka civil war.

Last night, Channel 4 News sent the panel a new Sri Lanka execution video which apparently shows government troops executing Tamils in the last few weeks of the war.

The video is a longer version of one which already sparked a United Nations (UN) investigation 16 months ago when it first came to light.

The UN Special Rapporteur on extrajudicial, summary or arbitrary executions, Professor Christof Heyns, told Channel 4 News futher investigations were needed into the Sri Lanka video.

"It is shocking indeed, and clearly deserves more investigation," he said.

Channel 4 News Foreign Affairs Correspondent Jonathan Miller said: "The rest of the video is too gruesome to broadcast: women bound, shot dead, undressed; callous comments from onlookers laden with sexual innuendo. Since Channel 4 News received and broadcast the executions video over a year ago we have received hundreds of photographs and many more shocking videos depicting summary executions and rape.

"We've now sent this five minute 30 second video to the UN panel convened to determine whether or not there should be an independent international war crimes inquiry."

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The video appears to show the same incident as one aired 16 months ago by Channel 4 News, which the Sri Lankan government says is a fake. It shows the execution of men in a muddy field, allegedly defeated Tamil prisoners. A UN investigation later found that the video "appeared authentic".

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 to reveal the naked and dead bodies of at least seven women, with accompanying dialogue from onlookers who make lewd and callous comments which seems to strongly suggest that sexual assaults have taken place before the death of the women.