BEIRUT // An international rights group yesterday accused some in Syria's opposition of serious abuses, including kidnapping and torturing security forces, in a sign of the growing complexity of the uprising.
Human Rights Watch's statement comes as Syria's rebellion transforms into an insurgency, with army defectors and government opponents taking up arms.
The development has added a violent dimension to a conflict that has killed 8,000 civilians in a year and 2,000 of the government's forces.
"The Syrian government's brutal tactics cannot justify abuses by armed opposition groups," said Sarah Leah Whitson, the Middle East director at Human Rights Watch.
The revolt began with mostly peaceful protests against the government, inspired by the Arab Spring uprisings across the region.
But the regime responded violently, firing on protesters and rounding up thousands of protesters. Bashar Al Assad, the Syrian president, has justified the response by saying terrorists were driving the revolt.
But the opposition denies that, saying Mr Al Assad's opponents have been forced to take up weapons because of the regime's violence.
Human Rights Watch made yesterday's statement in an open letter to the opposition Syrian National Council (SNC). The group stressed that many of the anti-government groups reported to be carrying out abuses did not appear to belong to an organised command structure or to be following orders from the SNC, the main opposition group.
But the SNC's leadership has a responsibility to speak out and condemn such abuses, Human Rights Watch said. The group also said it has received reports of executions by opposition groups.
The most potent armed force fighting Mr Al Assad's regime is the Free Syrian Army, made up of army defectors - including nine generals - and others. But there are other, smaller groups operating as well.
The report cited witnesses who told Human Rights Watch that armed groups identifying themselves with the opposition had been kidnapping civilians and members of the security forces.
An activist identified as Mazen said three people who worked with the government had been tortured to death in Idlib. Another Syrian activist, Samih, told Human Rights Watch that members of the Free Syrian Army were kidnapping soldiers.
"They would kidnap them and ask their parents to pay a ransom to let them go," he said.
The Free Syrian Army denied kidnapping soldiers, saying they were detaining them during military operations.
Russia said yesterday it was ready to support a UN resolution and endorse a plan by special UN and Arab League envoy Kofi Annan, signalling it would be prepared to raise the pressure on its old ally.