"It [political solution] cannot be achieved without setting aside the narrow national interests of a few that sometimes motivate their involvement in this war," Paulo Pinheiro, chair of the UN Commission of Inquiry for Syria, told the UN Human Rights Council.
Claiming that there are a lot of individuals and states that continue supporting the parties in the conflict with more money, weapons and training of combatants, Pinheiro warned that "without peace and justice in Syria, all the world will suffer more the consequences of this conflict".
The report alleges that all warring parties including government and non-governmental armed forces and ISIS have deliberately targeted civilian areas.
"The warring parties' failure to protect civilians has led to unspeakable suffering," the Commission said in its paper, adding Syrian President Bashar al-Assad government's bombing of civilian areas constitutes war crimes.
More From This Section
"In particular, the continuing use of barrel bombs in aerial campaigns against whole areas, rather than specific targets, is in violation of international humanitarian law and as previously documented, amounts to the war crime of targeting civilians," the report said.
Syrian Ambassador Hussam Eddin Aala rejected the findings, calling it biased for not pulling up Turkey, Saudi Arabia and Qatar for supporting rebels fighting against the Assad regime.
The investigators called the continuing war "a profound failure of diplomacy" and said that "the absence of decisive action by the community of States, as a whole - and the Security Council in particular - has nourished a now deeply entrenched culture of impunity".
The investigators, who have collected a huge database of 4000 interviews with victims and witnesses as well as names of perpetrators, have repeatedly appealed to UN Security Council to refer these cases of abuses to the International Criminal Court, but to no effect.