India on Monday said it was "inclined" to vote in support of a US-backed move at the UN Human Rights Council to push Sri Lanka to probe alleged war crimes in the final stages of its civil war.
Prime Minister Manmohan Singh said India, a traditional ally of Sri Lanka, expected the island to take "constructive measures for healing (the) wounds of conflict and bringing lasting peace" with ethnic Tamil people.
Sri Lanka has faced strong international criticism over the bloody finale of its separatist war against the Tamil Tiger rebels in 2009 but has avoided censure at previous UN meetings thanks to support from China and Russia.
The draft resolution, due to be voted on on Friday, urges Sri Lanka to ensure "justice, equity, accountability and reconciliation" and says Colombo's own probe did not adequately address concerns.
Singh said his embattled government, which is backed by a powerful regional Tamil party, was likely to endorse the US-backed resolution.
"I may assure the house we are inclined to vote in favour of the resolution.... for equality, dignity, justice and self respect," Singh told the parliament in New Delhi.
Sri Lanka has said it is confident of winning Friday's vote at the UNHRC sessions in Geneva.
Rights groups say up to 40,000 civilians were killed in the final months of the Sri Lankan military campaign to crush the Tamil rebels, who had waged a decades-long battle for a separate homeland for the island's minority Tamils.
The UN estimates some 100,000 people died during Sri Lanka's ethnic conflict between 1972 and 2009.