By Imogen Foulkes BBC News, Geneva

	HRW said some senior LTTE are missing since arrested by Sri Lanka forces

It documents the closing weeks of the 25 year conflict between Sri Lankan government forces and Tamil Tiger rebels.

The film, Sri Lanka’s killing fields, contains shocking video footage allegedly showing government troops executing Tamil prisoners – evidence, the film makers and human rights groups say, of war crimes and crimes against humanity which the UN must investigate.

Appalling images from the end of Sri Lanka’s long civil conflict: Tamil prisoners, naked, hands bound, being shot in the head. By, the new film claims, the Sri Lankan army.

But premiering this film at the United Nations human rights council prompted a furious response from Sri Lanka.

Furious response

Deputy Solicitor General A H Nawas insists the films of the killings are fake.

It is a fake on the basis of the initial investigations that has been done. This commission is ready and willing and if that is evidence that emerges certainly the prosecution will be launched Deputy Solicitor General A H Nawas

“It is not authentic. It is not authentic. Further investigations are ongoing on the footage,” he said.

“It is a fake on the basis of the initial investigations that has been done. This commission is ready and willing and if that is evidence that emerges certainly the prosecution will be launched.”

But this documentary is an hour long – it contains interviews with witnesses to the deliberate shelling of hospitals, to the rape of Tamil women, and to the torture and killing of prisoners of war.

And, says director Callum Macrae, the horrific video footage which accompanies the testimonies is authentic.

	Human rights activists say the need of the hour is a genuine investigation

“It is not fake. It has been very carefully analysed by forensic pathologists lokking at the nature of the wounds and by video scientists who analysed every frame of it, worked out when it was filmed, checked for any kind of editing,” he said.

“That footage is genuine evidence of genuine executions.”

The question is, what should the international community do – presented with evidence of war crimes which the relevant member state insists is false?

Sam Zafiri of Amnesty International warns that doing nothing is not an option.

“One of the terrible outcomes of this conflict and the impunity that followed is that it is about to establish a negative precedent around the world,” said Mr Zarifi.

Human rights activists point to the speed with which the UN acted over Libya – sending a team to investigate human rights violations, and referring Colonel Gaddafi to the international criminal court.

The atrocities documented in the Sri Lanka film deserve, they argue, at least the same attention.