He said an inquiry into the conduct of Sri Lankan troops and Tamil Tiger rebels could be conducted along the lines of the Gaza investigation commissioned by the U.N. Human Rights Council and led by jurist Richard Goldstone.

His comments came the day after the U.S. State Department detailed atrocities toward the end of Sri Lanka's civil war.

That report recounted allegations of military shelling of civilians and killing of captives, as well as charges that Tamil rebels recruited children to fight in the war that Colombo officially declared over in May after killing the leader of the Liberation Tigers of Tamil Eelam (LTTE).

Sri Lanka rejected the report, which Washington emphasised reached no legal conclusions, as "unsubstantiated and devoid of corroborative evidence" and said LTTE supporters had a history of fabricating stories to damage the government's reputation.

Colville, speaking to a U.N. press briefing in Geneva, said that while the State Department findings were not exhaustive, it was important to credibly lay out what civilians endured as Sri Lanka's conflict neared its end.

"We still believe that something like the Gaza fact-finding mission is certainly warranted," he said.

In late May, the U.N. Human Rights council passed a resolution celebrating Sri Lanka's victory over the Tamils and blocked discussion on a European-drafted text raising concerns about the conditions endured by war survivors housed in Sri Lankan camps.

Sri Lanka said the vote vindicated its prosecution of the war against the Tamil Tigers and should silence calls for a foreign probe into what it described as the Indian Ocean country's own internal affairs.

But the United Nations -- which estimates between 80,000 and 100,000 people were killed in Sri Lanka since civil war erupted in full in 1983 -- had then signalled that an inquiry could still happen down the line.

The International Organisation for Migration said on Friday that more than 250,000 people cannot return to their Sri Lankan villages and remain at the Manik Farm displacement camp, where they need continuing food, water and medical help. (Reuters)

A related news from AFP added that the UN human rights office also urged the Sri Lankan government to honour pledges that it would allow displaced Tamils out of government-run camps and seek to reduce discrimination against the Tamil minority.

"The issue of some 240,000 - 250,000 displaced people living in what are in effect internment camps continues to be of great concern, we hope the government takes serious actions to fulfill these commitments in the very near future" said Colville