"The commission believes that orders to shoot and otherwise mistreat civilians originated from policies and directives issued at the highest levels of the armed forces and the government," the panel said in its report.
Chairman Paulo Pinheiro told a press conference in Geneva: "Members of the Syrian army and security forces have committed crimes against humanity in their repression of a largely civilian population in the context of a peaceful protest movement.
"These crimes include murder, torture, rape and imprisonment.
"The commission has also concluded that the widespread and systematic violations of human rights in Syria could not have happened without the consent of the highest-ranking state officials."
Defectors from military and security forces told the commission that they received orders to shoot at unarmed protesters without warning.
They had conducted joint operations with loyalist militias with "shoot to kill" orders, notably in Latakia in early April and in a suburb of the same port city in August.
"The protesters called for freedom. They carried olive branches and marched with their children," a witness was quoted as saying.
"We were ordered to either disperse the crowd or eliminate everybody, including children. We opened fire."
The panel heard of sniper attacks on people leading marches and on those trying to rescue the wounded.
Torture and killings reportedly took place in the Homs Military Hospital by security forces dressed as doctors and abuse of detainees was described as "rampant" at the detention facilities of the Air Force Intelligence Branch at Mazzeh airport near Damascus.
The report highlighted the case of 14-year-old detainee Thamir Al Sharee from the town of Sayda whose postmortem showed injuries consistent with torture.
A 40-year-old man told the panel he witnessed the rape of an 11-year-old boy by three security services officers.
The commission said Syria had violated the right to life, to peaceful assembly and to freedom of movement among others.
It called on the government to put an "immediate end to gross human rights violations" and launch an independent investigation into the violence.
The report also acknowledged the existence of the "Free Syrian Army," a group of defectors it said had claimed responsibility for armed attacks against military and security forces and in its list of recommendations the panel urged opposition groups to respect international human rights law.
The Human Rights Council set up the commission in August to investigate human rights violations in Syria where the UN estimates at least 3,500 people have been killed.
The panel met with regional organisations including the Organization of the Islamic Conference and the Arab League as it gathered evidence from the end of September to the middle of November but was not allowed to carry out its work inside Syria.
The council will study the report by the three experts, Brazilian Pinheiro, Karen Koning AbuZayd from the United States and Turk Yakin Erturk at an extraordinary session to be arranged "very soon", a French diplomatic source said.
A statement by the US representative to the UN Human Rights Council, ambassador Eileen Chamberlain Donahoe, said the report "amplifies an already growing chorus of international condemnation and call for action".
"It is clear to anyone who reads it that Assad's unwillingness to end his regime's violence is taking Syria down a very dangerous path despite efforts led by the Syrian people to start a peaceful transition to democracy," she said.
Human Rights Watch and Amnesty International Monday called for the UN Security Council to take action on the Syria case and refer it to the international war crimes court.
"The Human Rights Council should take the necessary steps to support implementation of the commission's recommendations, including calling on the UN Security Council to impose targeted sanctions and refer the situation in Syria to the International Criminal Court," said HRW specialist Philippe Dam.
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Chairman Paulo Pinheiro told a press conference in Geneva: "Members of the Syrian army and security forces have committed crimes against humanity in their repression of a largely civilian population in the context of a peaceful protest movement.
"These crimes include murder, torture, rape and imprisonment.
"The commission has also concluded that the widespread and systematic violations of human rights in Syria could not have happened without the consent of the highest-ranking state officials."
Defectors from military and security forces told the commission that they received orders to shoot at unarmed protesters without warning.
They had conducted joint operations with loyalist militias with "shoot to kill" orders, notably in Latakia in early April and in a suburb of the same port city in August.
"The protesters called for freedom. They carried olive branches and marched with their children," a witness was quoted as saying.
"We were ordered to either disperse the crowd or eliminate everybody, including children. We opened fire."
The panel heard of sniper attacks on people leading marches and on those trying to rescue the wounded.
Torture and killings reportedly took place in the Homs Military Hospital by security forces dressed as doctors and abuse of detainees was described as "rampant" at the detention facilities of the Air Force Intelligence Branch at Mazzeh airport near Damascus.
The report highlighted the case of 14-year-old detainee Thamir Al Sharee from the town of Sayda whose postmortem showed injuries consistent with torture.
A 40-year-old man told the panel he witnessed the rape of an 11-year-old boy by three security services officers.
The commission said Syria had violated the right to life, to peaceful assembly and to freedom of movement among others.
It called on the government to put an "immediate end to gross human rights violations" and launch an independent investigation into the violence.
The report also acknowledged the existence of the "Free Syrian Army," a group of defectors it said had claimed responsibility for armed attacks against military and security forces and in its list of recommendations the panel urged opposition groups to respect international human rights law.
The Human Rights Council set up the commission in August to investigate human rights violations in Syria where the UN estimates at least 3,500 people have been killed.
The panel met with regional organisations including the Organization of the Islamic Conference and the Arab League as it gathered evidence from the end of September to the middle of November but was not allowed to carry out its work inside Syria.
The council will study the report by the three experts, Brazilian Pinheiro, Karen Koning AbuZayd from the United States and Turk Yakin Erturk at an extraordinary session to be arranged "very soon", a French diplomatic source said.
A statement by the US representative to the UN Human Rights Council, ambassador Eileen Chamberlain Donahoe, said the report "amplifies an already growing chorus of international condemnation and call for action".
"It is clear to anyone who reads it that Assad's unwillingness to end his regime's violence is taking Syria down a very dangerous path despite efforts led by the Syrian people to start a peaceful transition to democracy," she said.
Human Rights Watch and Amnesty International Monday called for the UN Security Council to take action on the Syria case and refer it to the international war crimes court.
"The Human Rights Council should take the necessary steps to support implementation of the commission's recommendations, including calling on the UN Security Council to impose targeted sanctions and refer the situation in Syria to the International Criminal Court," said HRW specialist Philippe Dam.
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