COLOMBO: Sri Lanka on Sunday rejected growing calls to probe human rights violations amid allegations that thousands of civilians perished in the final battle against Tamil separatists.

Media Minister Lakshman Yapa Abeywardena said organisations calling for investigations had "ulterior motives," and dismissed demands for independent probes into the final phase of Sri Lanka's war against Tamil separatists.

"Those who give various civilian casualty figures and call for these probes must have ulterior motives," Abeywardena told reporters here.

He said the government itself was in the process of assessing the civilian casualties, but gave no figures.

"Our officials knew how many people were in the (war zone) area and we are taking a tally on the number of people now in the IDP (internally displaced persons) camps," Abeywardena said.

His remarks came a day after the London-based rights group, Amnesty International, called for an independent probe into the number of civilians killed while government forces crushed Tamil Tiger rebels two weeks ago.

Amnesty also urged the United Nations to reveal its own estimates for civilian casualties.

The rights group's Asia Pacific director Sam Zarifi accused both sides of war crimes and called for an independent international probe.

A report in the Times of London newspaper on Friday citing confidential UN reports said that more than 20,000 non-combatants were killed by Sri Lankan army shelling in May.

Sri Lanka rejected the Times report as "way out" and managed last week to defeat a censure move by Western nations before the UN human rights council in Geneva.

Amnesty said it continues to receive reports of widespread human rights violations, with more than 280,000 people displaced by the recent fighting and now restricted to state-run camps in the island's north.