Sri Lanka has dismissed calls for an independent inquiry into claims of human rights abuses by the military, saying its own courts will investigate.
Foreign minister Rohita Bogollagama said claims that heavy weaponry was used in civilian areas during the war with Tamil rebels were "fictional".
He said the claims were being used to boost accusations of genocide against the country's Tamil minority.
Aid agencies and the United Nations have called for an inquiry.
The BBC reports the exact number of civilians killed in the final weeks of the long-running war has not been established, but one report put it as high as 20,000.
Mr Bogollagama said the accusations were intended to discredit the armed forces and embarrass the government of Sri Lanka.
Government forces were ordered to stop using heavy weapons on 27 April.
From that time onwards they were supposed to observe a no-fire zone where 100,000 Tamil men, women and children were sheltering.
Sri Lanka declared declared victory over the rebels on 18 May.
The UN said on Friday the world will probably never find out how many innocent civilians died during the final phase of the war, which began in 1983.