Syrian government forces have executed entire families in their homes as part of a crackdown on the uprising against President Bashar al-Assad, UN investigators have said.
They said Assad's troops and opposition fighters were committing gross human rights violations despite a six-week-old ceasefire in the conflict.
However, the army and security forces were responsible for most of the crimes documented since March.
The UN report also found that children were often victims.
Government abuses included heavy shelling of residential areas, executions and torture.
Syrian forces routinely drew up a list of wanted persons and their families before blockading and then attacking a village or neighbourhood, the report said.
Rebels, who are increasingly armed and well-organised, have executed or tortured captured soldiers and pro-government supporters, it said.
They have also abducted civilians in an apparent bid to secure prison exchanges or ransoms.
"Most of the serious human rights violations documented by the commission in this update were committed by the Syrian army and security services as part of military or search operations conducted in locations known for hosting defectors and/or armed persons, or perceived as supportive of anti-government armed groups," the report said.
Children were frequently among those killed and wounded during attacks on protests and the bombardment of towns and villages by state forces, it said.
"Entire families were executed in their homes - usually the family members of those opposing the government such as the family members of Colonel Riad al-Asaad," it said, referring to the extended family of the head of the Free Syrian Army.
The team of investigators, led by Brazilian Paulo Pinheiro, has not been allowed into Syria but based its report on more than 200 interviews of victims and witnesses.
They confirmed 207 deaths during the two-month period.
The United Nations has said that as of December, government forces had killed more than 9,000 people in the uprising against Assad that began in March 2011.
The world body is deploying up to 300 unarmed military observers in Syria to monitor a 12 April truce mediated by UN-Arab League envoy Kofi Annan that has yet to take hold.
