The investigators claimed that they had drawn up a new secret list of Syrians and military units suspected of committing war crimes and should face criminal prosecution some day.
According to Reuters, the independent investigators, led by Paulo Pinheiro, said they had gathered "a formidable and extraordinary body of evidence."
"A second confidential list of individuals and units believed to be responsible for violations is being provided to the High Commissioner of Human Rights," Pinheiro is quoted by the UK based news agency as telling the UN Human Rights Council in Geneva.
He did not say if any Syrian rebels, as well as officials, were named on the list, which updated a confidential one his team submitted to UN rights Chief Navi Pillay in February 2012.
Pinheiro presented the team's latest report, issued a month ago, saying Syrian government forces and allied militia have committed war crimes including murder and torture of civilians in what appears to be a state-directed policy.
He said there was an "increasing and alarming presence" of Islamist militants in Syria, some joining the rebels and others operating independently.
In July 2012, Pillay made a similar call to the Security Council, believing that crimes against humanity were being committed by government forces and armed opponents in the ongoing conflict.
Her appeal was followed by a move of the UN Human Rights Council, condemning the situation in Syria, after noting gross violations of human rights. The UN estimates that more than 10,000 people, mostly civilians, have been killed in Syria and tens of thousands displaced since the uprising against President Bashar al-Assad began.