The footage shows the men - bound, blindfolded and all but one naked - lying and sitting on the ground. They are shot at close range by men in military camouflage.
The U.N. special investigator on extra-judicial killings has called for the government of Sri Lanka to conduct an independent investigation into a videotape that appears to show the summary execution of nine ethnic Tamils by Sri Lankan soldiers.
The videotape aired in August by British Television Channel 4. The footage shows the men - bound, blindfolded and all but one naked - lying and sitting on the ground. They are shot at close range by men in military camouflage.
At the time the videotape aired, the Sri Lankan government "categorically" denied its armed forces engaged in any atrocities against ethnic Tamils. It said their war was only against elements of the Tamil rebels of the LTTE.
Special Rapporteur Philip Alston told reporters he had the tape examined by three independent U.S.-based experts - a forensic pathologist, a firearms specialist and a video analysis expert.
"Each of these experts subjected the videotape to a very careful and thorough examination," he said. "And each of them concluded that there was nothing to indicate that the video was a fake. My own interpretation of their conclusions is that they point very clearly to the authenticity of the video."
He said that while there were some unexplained elements in the tape, such as the date that was encoded in the tape, placing it after the end of the conflict, he said they could be explained in a manner "entirely consistent" with the conclusion that the tape is authentic.
Alston called for the government of Sri Lanka to respond to the allegations.
"In light of the persistent flow of other allegations of extra-judicial executions committed by both sides during the closing phases of war against the LTTE, I call for an independent inquiry to be established to carry out an impartial investigation into war crimes and other grave violations of international humanitarian and human rights law allegedly committed in Sri Lanka," he said.
The Colombo government previously commissioned a four-person panel of Sri Lankans to examine the tape. Alston said two of the panelists were members of the army - the very group under scrutiny. They unanimously deemed the tape a fake.
Sri Lanka's U.N.misssion First Secretary, Political Affairs Maxwell Keegel criticized the U.N. investigator for holding a press conference to announce his findings less than 24 hours after he had given the report to Colombo.
"Without giving sufficient time for the government to respond, he has rushed to brief the public and, therefore, we feel that he has rushed in this manner," he said. "[It] makes us feel that he is pursuing his own agenda."
Meanwhile, U.N. Secretary-General Spokesman Martin Nesirky said Ban Ki-moon is considering appointing a commission of experts on the matter.
"The Secretary-General has informed the Sri Lankan Government that he is considering the appointment of a commission of experts to advise him further and to assist the government in taking measures to address possible violations of international human rights and humanitarian law," he said.
He said the United Nations is ready to assist the Sri Lankan government in conducting a full and impartial investigation into allegations of human rights violations.