There are fresh calls for an inquiry into the death of the 12-year-old son of Tamil Tiger rebel leader Velupillai Prabhakaran in the last weeks of Sri Lanka's civil war.
Britto Fernando, co-convenor for the Platform for Freedom and president of the Families of the Disappeared, has told Radio Australia's Asia Pacific there should be an inquiry into atrocities committed by both sides during the war.
"We want to say that, not only the government (should be investigated), maybe the LTTE (Liberation Tigers of Tamil Eelam), even though they were fighting for their people, they did commit a lot of wrong things," he said.
A British film-maker on Tuesday released photographs allegedly of Balachandran, the Tamil Tiger rebel leader's son, to publicise a new documentary on war crimes for Britain's Channel Four.
The documentary alleges the boy was executed two hours after the first photo was taken.
The UN Human Rights Council meets in Geneva next month and the Sri Lankan army says allegations tend to surface to coincide with the meetings.
Director Callum Macrae says the pictures, part of a documentary for Britain's Channel 4, prove the Sri Lankan army's involvement in war crimes including summary execution and torture.
The island nation suffered a 37-year-long civil war.
Mr Macrae says the pictures "tell a chilling story", in an article he published in Indian newspaper, The Hindu.
In one picture, Balachandran, the son of the slain rebel leader, is seen eating a snack while sitting in a green sandbag bunker guarded by a soldier.
A second image shows his bullet-riddled bare-chested body.
The documentary alleges Balachandran was executed two hours after the first photo was taken.
Mr Macrae said the images have been scrutinised by digital image analysts, who concluded they came from the same camera, and support video footage of the boy's body uncovered last year.
The Sri Lankan government has maintained that Velupillai Prabhakaran's family was killed in fighting.
The bodies of his wife and daughter have never been found.
"No War Zone: The Killing Fields of Sri Lanka" will be released in March in Geneva to coincide with a UN Human Rights Council discussion on the country.
Sri Lanka is currently facing censure by the United States over its failure to probe war crimes.
Sri Lanka's military denied executing prisoners and accused the British network of engaging in a campaign to tar the country's reputation.