UN report says "new levels of brutality."

"War crimes, crimes against humanity and gross human rights violations continue apace," it added, reporting 17 incidents that could be called massacres between mid-January and mid-May.

The panel cited increasing use of indiscriminate weapons, including cluster munitions, barrel bombs and surface-to-surface missiles as evidence of the "flagrant disregard" of government forces for the distinction between combatants and civilians demanded by international law.

"crimes that shock the conscience have become a daily reality," Mr. Pinheiro said, reciting a list of abuses that included murder, extrajudicial execution, torture, recruitment of children and hostage taking.

There was a disparity between the abuses and crimes committed by government forces and militia and those conducted by rebel groups, he acknowledged, "but this is a disparity in intensity, it is not a disparity in the nature of the crimes." He added, "They are the same."