The minister denied that government forces were firing into a demarcated "safe zone" for civilians and accused UN human rights chief Navi Pillay of relying on pro-rebel elements to arrive at her assessment.
Pillay said in a statement Friday that she feared both sides could be guilty of war crimes in the Sri Lanka conflict and that more than 2,800 civilians may have been killed since late January.
"It is very, very unprofessional of her (Pillay's) office to rely on unsubstantiated figures," minister Samarasinghe told reporters here.
"The figures are similar to those on Tiger proxy websites."
"The army is not shelling into the safe zone for civilians."
Government forces say they have trapped Tamil Tiger rebels into a narrow strip of coastal land in the northeastern district of Mullaittivu where they hope to completely crush the guerrillas by next month.
Sri Lankan authorities have accused the Tigers of holding some 70,000 civilians hostage in the tiny territory still under