Sri Lankan pro-government activists protested outside the US embassy in Colombo Thursday as the UN Human Rights Council was set to vote on a resolution pressing for a war crimes probe against Sri Lanka.
Hundreds of demonstrators held up traffic outside the US embassy, close to Sri Lankan President Mahinda Rajapakse's official residence and chanted slogans denouncing US President Barack Obama and India's Prime Minister Manmohan Singh.
They carried photos of the two leaders with the caption: "Two idiots or two bastards."
The Federation of National Organisations, led by a key ruling party ally, marched to the area carrying placards denouncing the US for moving the censure resolution in Geneva and India for backing it.
India promised Wednesday to push for a "strong" UN resolution urging Sri Lanka to investigate allegations that up to 40,000 civilians were killed by government forces in the final months of fighting that ended in May 2009.
The US is drafting the resolution that is expected to be voted on later Thursday and is bound to anger Colombo which insists that no civilian was killed by its troops while crushing Tamil rebels known for trade mark suicide bombings.
The US has been highly critical of Sri Lanka's human rights record and has refused to train several of its senior military officers, saying they were linked to credible allegations of war crimes and crimes against humanity.
India, home to millions of Tamils who share links with their counterparts in Sri Lanka, risks a further worsening in relations with its southern neighbour over the UNHRC resolution.
Leader of the ruling Congress party, Sonia Gandhi, said Tuesday that India was "most pained" that Tamils in Sri Lanka were being denied their rights and New Delhi was "anguished by reports of unspeakable atrocities".