Sri Lanka is facing fresh calls for an international human rights inquiry after video emerged apparently showing extra-judicial killings by troops.
The footage was allegedly filmed in January during the final stages of the bloody conflict with the Tamil Tigers.
It shows a man dressed as a soldier shooting a naked man in the head. Eight other bodies are seen on the ground.
It is impossible to verify the video’s authenticity. Sri Lanka’s government says the footage was fabricated.
Call for access
It is not clear where the film was shot or when.
The footage 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".
Government troops finally declared victory over the Tamil Tigers (LTTE) in May after months of fierce fighting.
Journalists for Democracy in Sri Lanka said the video had been taken in January 2009.
The group is based in Europe and was recently formed by Sri Lankan journalists, both Sinhalese and Tamil, who have fled the country.
Nearly 50 journalists have done so in recent months because of fears of persecution by the government.
Independent media were banned by the government from travelling to the conflict zone in northern Sri Lanka.
Human rights group Amnesty International responded to the release of the video by repeating its call for "an international, independent and credible investigation into what took place during the final days of the conflict".
"Amnesty International has received consistent reports that violations of the laws of war, as well as international human rights law, were committed by both sides in the conflict," a statement said.
"The government of Sri Lanka must allow immediate access to the conflict area so that evidence and documents, as well as testimony from survivors, can be gathered."
‘Terrorists’
Sri Lanka’s military said the video was aimed at discrediting the armed forces and said the rebels were known to dress in military uniforms.
The government categorically denied that troops had carried out atrocities and suggested the footage had been fabricated by pro-rebel groups.
"The Sri Lankan army never engaged with Tamil civilians. Our fight was with the LTTE terrorists," High Commissioner to Britain Nihal Jayasinghe told the BBC.
He said "well-documented evidence" of human rights violations was needed before there could be any United Nations inquiry.
Both sides in Sri Lanka’s conflict have been accused of numerous atrocities and human rights violations over the years.
Many killings have also been blamed on proxy militias said to be working for one side or the other.
The UN estimates that more than 80,000 people were killed in the decades-long ethnic conflict.
The rebels were fighting for a separate state for Tamils in Sri Lanka’s north and east.
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