BEIRUT — An international human rights group says members of Syria's armed opposition have subjected detainees to torture and committed extrajudicial or summary executions in several areas.

Human Rights Watch says such incidents occurred in the northern provinces of Idlib and Aleppo and the coastal region of Latakia.

The New York-based group said in a report Monday that torture and extrajudicial or summary executions of detainees in the context of an armed conflict are war crimes, and may constitute crimes against humanity if they are widespread and systematic.

The group documented more than a dozen extrajudicial and summary executions by opposition forces.

HRW said three opposition leaders who were confronted with evidence of extrajudicial executions said those who killed deserved to be killed, and that only the "worst criminals were being executed."