In response to the video "Sri Lanka's Killing Fields: War Crimes Unpunished", the defence ministry re-released several videos and documents to counter the claims, reported Xinhua.
"The ministry categorically rejects the video as baseless and unacceptable," a defence ministry statement said.
The new video has former British foreign secretary David Miliband and the former head of UN Humanitarian Affairs John Holmes speaking on some of the incidents which took place during the final stages of the war in 2009.
The video blames both the government and the military over some of the incidents, including the failure to send adequate humanitarian aid to the thousands of civilians trapped in the final battle zone.
Sri Lanka says the video has been released with the intention of defaming the government at the ongoing UN summit for Human Rights in Geneva.
"The defence ministry rejects all allegations of human rights violation, stating that it is able to prove with valid evidence that it was the LTTE (Liberation Tigers of Tamil Eelam) that committed gross violation of human rights over the past three decades," it said.