Syrian security forces and insurgents are both carrying out unlawful killings, torturing opponents and abusing children, a UN-appointed panel of human rights experts charged on Thursday.
The findings by the Independent International Commission of Inquiry on Syria revealed a chilling pattern of abuse on both sides of the conflict.
The commission is chaired by Brazilian professor Paulo Sergio Pinheiro and includes Karen AbuZayd, former head of the UN agency for Palestinian refugees, and Yakin Erturk, a former UN investigator on violence against women.
Their report is based on hundreds of interviews since March with victims and witnesses who fled the country.
Human rights abuses by government forces occur "most often during large-scale, military attacks on specific locations known for hosting defectors and other anti-government sympathisers," it said.
The report also highlighted a growing list of abuses committed by insurgents, including summary executions of soldiers, police and suspected informers. It noted that the rebels have increasingly resorted to improvised explosive devices.
The panel said it had videotaped sessions in which captured Syrian government forces or supporters are seen confessing under torture.
And it said that insurgents have also abducted civilians and government forces for prisoner exchanges or ransom.
Syria's main opposition council has accepted the resignation of its Paris-based president who had earlier offered to step down amid mounting criticism of his leadership.
The Syrian National Council executive committee asked Burhan Ghalioun to pursue his duties until a new president is elected at a meeting on June 9 and 10.
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