The probe by the Office of the High Commissioner for Human Rights is “utterly uncalled for”, says Sri Lanka.

“We have taken the view that this investigation is utterly uncalled for,” UN Ambassador Palitha Kohona, said according to the Associated Press.

“It’s like this poor third-world country is being punished in an unforgiving manner for having defeated a terrorist group” he said.

Kohona has previously said that surrendering LTTE members, who are thought to have been shot by the military, were actually shot in the back by Tamil fighters.

But Kohona now distanced himself from those comments, saying that he doesn't personally know what happened.

He confirmed to AP that text messages were exchanged with an European intermediary with advice for on how to surrender, but he claimed he was not aware of a surrender deal, adding that he does not believe a kill order was issued by Defence Secretary of Sri Lanka, Gotabhaya Rajapaksa, who is also a US citizen, and executed by Major General Shavendra Silva, the commander of the army's 58th Division.

According to AP, the US Department of Justice declined to comment whether it has investigated the possible involvement of US citizens in war crimes on the island, under a war crimes statute passed in 1996.

"It is very easy to make allegations. It's very easy to find witnesses among those who have an axe to grind. But as to whether these carry any credibility is a different matter," said Kohona, a former attorney in Sri Lanka's supreme court.

“It is very easy to make allegations. It’s very easy to find witnesses among those who have an axe to grind. But as to whether these carry any credibility is a different matter,” Kohona said.

Silva, currently Kohona's deputy at Sri Lanka's mission at the UN, did not respond to a request for an interview with AP.