U.N. investigators said Tuesday they had expanded their list of suspected war criminals from both sides in Syria's civil war and the evidence was solid enough to prepare any indictment.

The U.N. inquiry has identified individuals, military units and security agencies as well as insurgent groups suspected of committing abuses such as torture and bombing civilian areas, it said in its report to the United Nations Human Rights Council.

Some 20 investigators have carried out 2,700 interviews with victims, witnesses and defectors in the region and by Skype in Syria, but have never been allowed to enter the country now in its fourth year of an increasingly sectarian conflict.