|The UK has a sizeable Tamil community which has been vocal about alleged atrocities during the war [EPA]
A British television channel has broadcast footage of an alleged massacre by Sri Lankan troops during the island's civil war, saying at least seven women may have been killed.
The broadcast on Tuesday coincided with a visit to the UK by Mahinda Rajapaksa, the Sri Lankan president, who is facing allegations of war crimes by Tamil activists.
Channel 4 said the five-minute video, of which it broadcast excerpts, showed the bodies of the dead women in a muddy field. It was an extension of another video shown by the channel last year in which soldiers appeared to shoot two blindfolded men.
"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.
It said the video had accompanying dialogue in which onlookers made "lewd and callous comments, which seems to strongly suggest that sexual assaults have taken place before the death of the women".
Last month, Al Jazeera broadcast pictures that appeared to show Sri Lankan army soldiers abusing Tamil civilians in the final days of the war.
They showed various graphic scenes, with dead bodies blindfolded and hands bound.
Sri Lankan denial
The Sri Lankan embassy in London said on Wednesday that the Channel 4 footage was not authentic.
Authorities had already dismissed the footage released last year, which was obtained from the Europe-based media lobby group Journalists for Democracy in Sri Lanka, as a "fabrication designed to discredit" its armed forces.
However, Philip Alston, the United Nations human rights envoy, concluded in January that the video, said to be of Sri Lankan troops executing unarmed Tamil Tiger rebels, was authentic.
The Sri Lankan president was greeted by hundreds of Tamil protesters as he landed in London on Monday.
Lawyers for Tamil activists in the UK are trying to obtain a war crimes arrest warrant against Rajapaksa, for atrocities allegedly committed by government troops in the final stage of the offensive against Tamil separatists.
Sen Kandiah, the founder of the British Tamil Forum, told the Guardian newspaper that the organisation had been working on an arrest warrant "for some time".
"We have instructed a prominent legal firm and have spoken to former lord chancellors," he said.
"We know that at least 40,000 civilians were killed at the end of the war. This man was the commander in chief ... He should face a proper trial."
But Al Jazeera's Emma Hayward, reporting from London, said: "It's unlikely that this will make much progress because he would have state immunity in the UK."
Rajapaksa was due to take part in a debate at Oxford University on Thursday.
"Thousands of Tamils are expected to take part in a protest there," our correspondent said.
Sri Lankan troops defeated the Liberation Tigers of Tamil Eelam (LTTE) in May 2009 after more than 25 years of fighting. The final military offensive triggered allegations of war crimes, with the UN, Western nations and rights groups pushing for a probe of possible violations by both sides.