Evidence confirms at least eight massacres have been perpetrated in Syria by President Bashar Assad’s regime and supporters and one by rebels over the past year and a half, a UN commission said on Wednesday.

Calling Syria a battlefield where “massacres are perpetrated with impunity,” the UN commission investigating human rights abuses in Syria said that in each of the incidents since April 2012 “the intentional mass killing and identity of the perpetrator were confirmed to the commission’s evidentiary standards.”

Its latest report also notes that the four-member commission is probing nine more suspected mass killings since March. With those, it said, the illegal killing was confirmed but the perpetrator could not yet be identified.

In other cases, it said, the circumstances of the killing were not sufficiently clear to be able to determine the legality.

The report updates the commission’s work since 2011 to mid-July, stopping short of what the United States says was an Aug. 21 chemical weapons attack on rebel-held areas that killed hundreds of civilians.

The commission created by the UN’s 47-nation Human Rights Council says both sides have committed heinous war crimes during the two and a half years conflict that has killed over 100,000 people. The council is due to take up the report and the commission plans to hold a news conference next week.

In a statement accompanying the report, the commission chaired by Brazilian diplomat and scholar Paulo Sergio Pinheiro said most casualties result from unlawful attacks using conventional weapons and any response to end the conflict “must be founded upon the protection of civilians.”

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