Sri Lanka said Friday it would protest to the United States over its allegations that army shelling killed hundreds of families during the final days of the island's ethnic civil war.
A senior foreign ministry official said the allegation, made in a US embassy tweet Thursday, would be discussed with visiting Ambassador for Global Criminal Justice Stephen Rapp.
"Our minister (G. L. Peiris) will take it up face-to-face with ambassador Rapp," the official told AFP, asking not to be named.
"It is a baseless allegation. It is uncalled for," he said.
Rapp arrived in Sri Lanka Monday on a five-day visit to meet officials and politicians to discuss Sri Lanka's rights record and attempts at reconciliation five years after the end of war.
The US embassy posted on Twitter a photo of Rapp and its ambassador Michele Sison from the island's former battle zone with the caption: "St Anthany's Ground - site of Jan 2009 killing of hundreds of families by army shelling."
US diplomats in Colombo told AFP the tweet reflected Washington's toughening human rights policy towards Sri Lanka.
"This tweet reflects official government stance," an embassy official said, speaking on condition of anonymity.
Sri Lanka has denied charges that up to 40,000 ethnic Tamil civilians were killed by the army during the final push that crushed Tamil rebels fighting for a separate homeland.
Sri Lanka maintains that not a single civilian was killed by troops and in November ordered a census of war casualties.
The country's main Tamil political party has rejected the count as a sham and says it will collate its own figures.
The UN estimates that the conflict for a separate homeland for ethnic Tamils in the Sinhalese-majority nation cost at least 100,000 lives between 1972 and 2009.