United Nations Secretary General Ban Ki-moon has urged Sri Lanka to "unite and heal the wounds" after two decades of war rather than celebrate its victory over the Tamil Tigers.
Ban, who on Friday met the 15 members of the UN Security Council to discuss the controversial end to the conflict in Sri Lanka, also called for a "proper investigation" into allegations of massive civilian deaths in the final days of the ethnic conflict at the end of May.
Human rights advocates and media reports have said up to 20,000 civilians were killed in the last phase of battle against the Liberation Tigers of Tamil Eelam (LTTE).
Ban warned the Sri Lankan government against engaging in celebrations, as Colombo revelled in the defeat of the Tamil Tigers.
"I take this opportunity to warn against the risk of triumphalism, which will really hinder the ongoing efforts by the Sri Lankan government, the people and the international community in helping to heal the wounds," Ban told reporters after the meeting.
"This is very important at this time to unite and heal the wounds rather than enjoy in celebrations in the wake of the end of the conflict," he said.
Ban said he had asked the Sri Lankan government to provide relief groups and the United Nations free access to the tens of thousands of Sri Lankans who are in need of assistance.
The UN High Commissioner for Human Rights in Geneva and advocacy groups like Amnesty International have called for an investigation based on allegations of high numbers of civilian deaths.
The closed-door meeting between Ban and the council members in a basement conference room at UN headquarters in New York was billed as an "informal interactive discussion on Sri Lanka". Neither side has said it will draw any conclusion from the debate.
Ban said in early June, after the Sri Lankan government declared victory over the LTTE, that he considered the civilian casualties "unacceptably high." He cited media reports alleging that the civilian deaths stood at 20,000.
Ban rejected criticism that the UN had played down the facts of the final onslaught as two decades of fighting between the government and LTTE was drawing to an end in May.
The UN has been involved in providing relief assistance to the hundreds of thousands of Sri Lankans trapped or displaced by the fighting.