Newly released images from Sri Lanka's civil war carry gruesome evidence which appears to implicate the country's military in war crimes.

A British documentary team has found photographic evidence of soldiers executing suspected Tamil Tigers at point-blank range.

Those killed include the 12-year-old son of dead Tamil Tiger leader Prabhakaran.

The UN Human Rights Council is debating whether Sri Lanka's military acted illegally during the final stages of the war.

The vision, set to be aired on Britain's Channel 4 later this week, was analysed by an independent forensics expert.

"So this is an execution scene with five men dead and a young boy," the expert says in the documentary.

"The five men, their arms are behind their backs, they're freshly dead. They look as if they've been tied but there's no ties visible except in the last man whom we see.

"This is the same pattern that we see in the other footage, where prisoners are tied with their hands behind their back, blindfolded, knelt on the ground and then shot."

The vision was taken in May 2009, just as Sri Lanka's military was in the process of mopping up in the final stages of the civil war.

Journalist and a former spokesman for the UN in Sri Lanka, Gordon Weiss, says the pictures show very powerful evidence of war crimes having been committed.

"It's visual evidence of a couple of specific murders that took place in the battlefield," he said.

"Now the government of Sri Lanka has always denied that its forces were guilty of any wrongdoing whatsoever, but in one of these sequences you see Sri Lankan military officers interrogating a senior Tamil commander before he is forced to change from civilian clothes into military fatigues and is then killed.

"In the other sequence you see the son of the former Tamil Tiger leader, Velupillai Prabhakaran, who has been shot dead on the ground and another five men who have been bound and shot next to him."

Call for accountability

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 36 seconds 4 m 36 s New images emerge of civil war atrocities Download 2.1 MB

In the final stages of the civil war, more than 300,000 Tamil civilians and fighters were trapped in a small pocket of coastal land in Sri Lanka's north.

The military is alleged to have deliberately shelled civilians and executed Tamil Tiger fighters after they surrendered.

Sri Lanka denies this, but the UN Human Rights Council is debating a number of resolutions which, if passed, would contradict Sri Lanka's official line.

Mr Weiss says Sri Lanka's government needs to be held to account.

"Something like this is inherently political anyway," he said.

"There are a number of resolutions before the council. One of them is asking for a very high level of accountability and is calling for an international investigation.

"The one that is most likely to pass is one that has been put forward by the US and it's again calling for real accountability from Sri Lanka, but it's giving a more extended timetable and more wriggle room really for the Sri Lankans."

'No basis'

Sri Lanka's government says the latest claims have no basis.

It describes the Tamil Tigers as terrorists and says no civilians have ever been deliberately targeted.

Colombo's High Commissioner to Australia, Admiral TSG Samarasinghe, says the Sri Lankan government has established its own investigation.

"We will be looking into any specific evidence and allegations which are coming forward by authentic channels," he said.

"So having said that, there has been no deliberate attempt by Sri Lankan authorities of any civilian being targeted deliberately.

"It was a long, long conflict, while rescuing 300,000 civilians from the clutches of terrorists who kept them as human shields for long years they were freed through a military offensive.

"So I reject any deliberate action by the government in targeting civilians and in the process creating any human rights violations."