Footage allegedly showing the killing of prisoners. Its authenticity cannot be verified. It has been edited here to remove the most disturbing images
Video apparently showing extra-judicial killings by Sri Lankan troops is genuine, a UN envoy has said.
UN special rapporteur Philip Alston said three independent experts had confirmed the video was authentic, renewing calls for a war crime inquiry.
The footage - which Sri Lanka says is fabricated - shows a man dressed as a soldier shooting a man in the head.
It was allegedly filmed in January during the final stages of the bloody conflict with Tamil Tigers rebels.
The government in Colombo said it concluded the video was fake after conducting its own investigation.
Bodies on ground
But Mr Alston, the UN special rapporteur on extra-judicial killings, told reporters: "The conclusion clearly is that the video is authentic."
He said the video had been examined by three US-based independent investigators.
He named them as Peter Diaczuk, an expert in firearms evidence, Daniel Spitz, a prominent forensic pathologist, and Jeff Spivack, an expert in forensic video analysis.
At the same time he noted that there were "a small number of characteristics of the video which the experts were unable to explain".
"Each of these characteristics can, however, be explained in a manner entirely consistent with the conclusion that the videotape appears to be authentic," he added.
The UN official also called on the Sri Lankan government to hold an independent inquiry into possible war crimes committed by both sides of the conflict.
It is not clear where the footage, which also shows other bodies on the ground, was taken.
The video was provided to the BBC and other media organisations by a group called Journalists for Democracy in Sri Lanka, which said it showed "the reality of the behaviour of the government forces during the war".
Journalists for Democracy in Sri Lanka said the video had been taken in January 2009 using a mobile phone.
Sri Lankan troops finally defeated the Tamil Tigers last May - after nearly 26 years of war.
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