GENEVA (Reuters) - Video footage of summary executions apparently committed during the Sri Lankan civil war appears to be convincing evidence of "serious international crimes," a U.N. special envoy said on Monday.
The charge adds to pressure on Colombo to submit to an international inquiry into allegations that thousands of civilians were killed at the end of its 25-year war with the Liberation Tigers of Tamil Eelam (LTTE).
Sri Lankan authorities have rejected the video as falsified and responded angrily to U.N. criticisms, accusing the body of bias and of meddling in Colombo's domestic processes.
It has acknowledged some non-combatants were killed, but says the numbers have been inflated by LTTE supporters.
A video provided by Britain's Channel 4 television shows naked people with their hands tied behind their backs being executed against a backdrop of corpses of other men and women.
Since late last year, the United Nations has studied the video that allegedly showed acts committed during the civil war that ended in 2009.
"I conclude on the basis of the extensive technical evidence we obtained from independent experts that what is depicted in the video indeed happened," Christof Heyns, the U.N.'s special rapporteur on extrajudicial, summary or arbitrary executions, told the Human Rights Council in Geneva. "I believe that a prima facie case of serious international crimes has been made," Heyns said. The evidence should be investigated by an international panel, he said.
He did not say what he meant by serious international crimes, which can be war crimes or crimes against humanity.
The video is a five-minute version of a minute of footage previously studied by the United Nations. Heyns said the longer version resolved "unexplained elements" in the first video.
Sri Lanka and the pro-LTTE diaspora have engaged in a propaganda war since well before the conflict ended, with numerous groups offering what they say is realistic footage or photographs of atrocities. Many later proved to be doctored.
The United Nations in April published the findings of a three-member panel Secretary General Ban Ki-Moon appointed to advise him on "issues of accountability."
The Sri Lankan government on Monday again accused the United Nations of seeking to pre-empt its own Lessons Learned and Reconciliation Commission (LLRC), which it noted predated the U.N. panel.
"It is disconcerting to note the haste with which some have sought to usurp the government of Sri Lanka's prerogative in deciding its domestic process," Minister of Plantation Industries Mahinda Samarasinghe, the head of the Sri Lankan delegation, told the Human Rights Council.
"We firmly believe that our home-grown process is capable of addressing the nuances of our unique situation," he said.
He also said the U.N. system needs to be free from bias.
"It is of paramount importance that high offices of the U.N. system are scrupulously impartial, independent and transparent and are seen to be so," he said.
Barely a month after the civil war ended, Sri Lanka shocked Western governments by engineering the adoption of a U.N. Human Rights Council resolution that praised its victory over the Tamil Tigers, a group on more than 30 nations' terrorism lists.
That defeated a European-backed resolution condemning the civilian deaths at the war's end, pushed by nations angry that Sri Lanka refused pressure for a ceasefire in the final months.
The United States has warned that failure to investigate credibly the allegations and establish genuine reconciliation could lead to an international war crimes investigation.
Diplomats involved with Sri Lanka see that as unlikely, given the backing it has from China and Russia on the U.N. Security Council, but the Human Rights Council could still move for an inquiry.
Additional reporting by Bryson Hull in Colombo; Editing by Louise Ireland