BEIRUT (AP) — 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.”

Also on Monday, an independent UN panel confirmed that an increasing number of ‘foreign elements,’ including jihadis, are now operating in Syria.

The investigative panel appointed by the Human Rights Council said some of these forces are joining armed anti-government groups while others are operating on their own.

The head of the panel, Brazilian diplomat and professor Paulo Sergio Pinheiro, told diplomats Monday in Geneva that “such elements tend to push anti-government fighters towards more radical positions.”

Activists say at least 23,000 people have been killed in Syria over the past 18 months.

Syrian authorities have blamed the anti-government uprising that began in March 2011 on a foreign conspiracy and accused some Gulf and Western countries of offering funding and training to the rebels, whom they describe as terrorists.

Copyright 2012 The Associated Press.