In one incident, 30 women were found in one house, apparently executed.
The report documented eight mass killings, attributing all but one to government forces. But it said both government and rebel fighters had committed war crimes including murder, hostage-taking and shelling of civilians.
With more than 100,000 dead in the Syrian war, there was little sign that reports of atrocities would spur international action until last month, when claims that President Bashar al-Assad’s forces had gassed hundreds of civilians sparked a threat of military strikes.
The killings in Baida and Ras al-Nabaa, two pockets of rebel sympathisers surrounded by villages loyal to Assad on the outskirts of the town of Banias, did not involve fighting with rebels and appeared designed to send a message of deterrence.
The UN investigators were not allowed into Syria, but they carried out 258 interviews with refugees, defectors and others, in the region and in Geneva, for their 11th report in two years.
In Baida, between 150 and 250 civilians were allegedly killed, including the 30 women. The report said rebels were not active in the area at the time.
“Testimonies were consistent that members of the National Defence Forces were actively involved in the raids and in many cases leading them,” the 42-page report said.
“There are reasonable grounds to believe that government forces and affiliated militias including the National Defence Forces are the perpetrators of the Baida massacre.”
The next day, as word spread that militia fighters were advancing with army support, hundreds of civilians tried to flee the neighbouring village of Ras al-Nabaa, but were pushed back at checkpoints. Government forces then shelled the village and militia fighters moved in.
“Civilians were captured and executed,” the report said, adding: “The operation did not occur in the context of a military confrontation. Government forces were in full control of the area.” It gave a figure of 150 to 200 dead in Ras al-Nabaa.
The Syrian government kept silent about the killings at the time but an anonymous Syrian intelligence officer acknowledged that the perpetrators were loyalists, including some from surrounding Alawite villages.
The only deliberate slaughter of civilians attributed to rebel forces was in June, when rebels captured Hatla in the eastern province of Deir al-Zor.
“Anti-government armed fighters conducted home invasions, killing and summarily executing many Shia including at least 30 civilians, among them children, women and elderly,” the report said.
The Syrian Observatory for Human Rights, a pro-opposition monitoring group that has reported abuses on both sides of the conflict, said at the time that 60 people had died in the attack.
The commission, led by Paulo Pinheiro of Brazil, urged the UN Security Council to hold perpetrators accountable for war crimes.
The investigators analysed photos, video and satellite imagery, as well as forensic and medical records, to draw up their report.
The team also verified the killing of 450 people during an offensive by government forces and Lebanese Hezbollah fighters to retake the strategic town of Qusair. Food and water were cut off during a siege, and the town was heavily shelled.
“Approximately half were civilians, killed in the shelling and aerial bombardment of the town in the early days of the offensive,” the report said.
Talks start over poison gas arsenal
Tense negotiations have begun on a proposed UN resolution that would put Syria’s chemical weapons under international control and end a diplomatic stalemate over a deadly suspected poison gas attack.
The plan for Syria to relinquish its chemical weapons, initiated by Russia, appeared to ease the crisis over looming western strikes against President Bashar al-Assad’s regime in Damascus.
But it has opened up a new potential for deadlock as Moscow, a close ally of the Syrian leader, rejected US and French demands for a binding UN resolution with “very severe consequences” for non-compliance.
In Damascus, a senior government official said the Russian proposal is still a “broad headline” that needs to be developed. He added that Syria was ready to sign the chemical weapons convention but not if such a move is imposed by foreign powers.
Cabinet minister Ali Haidar said Syria’s chemical weapons, which he described as “the nuclear of the poor”, were meant to achieve strategic balance against Israel, “an enemy that we’ve been fighting for more than 60 years”.
A French official close to President Francois Hollande said Russia objected not only to making the resolution militarily enforceable, but also to blaming the alleged chemical attack last month on the Syrian government and demanding that those responsible face an international criminal court.
Paris and Washington are pushing for a UN Security Council resolution to verify Syria’s disarmament – but Russia dismissed France’s proposal on Tuesday.
Alexandre Orlov, Russia’s ambassador to France, said: “We think that the proposal came together quickly, in haste.
“It’s sure there are chemical weapons on both sides. The important thing is to forbid them, put them under international control. Then we will see who uses them.”
ALBERT AJI and SYLVIE CORBET
More export licences for dual use chemical exports revealed
A further five licences have been issued over the past ten years for the export to Syria of so-called “dual use” chemicals, which can be used in the manufacture of weapons, it was disclosed last night.
But business secretary Vince Cable said that all of the licences predate the outbreak of the civil war in the Middle Eastern country in 2011, and said he was “confident” that the exports were for legitimate commercial purposes.
Mr Cable has come under fire in recent days over two licences which were granted in January 2012 for the export of sodium fluoride and potassium fluoride to Syria.
The licences were revoked in July 2012 after European Union sanctions were tightened, and the Business Department has said that none of the chemicals were shipped out. Yesterday, the House of Commons Committees on Arms Exports Control (CAEC) released a letter from Mr Cable detailing five further licences for sodium fluoride totalling 4,150kg.
In the letter, the business secretary said: “In the light of the recent and shocking use of chemical weapons by the Assad regime in Syria, I asked my officials to determine whether any other licences for chemicals had been granted for Syria over the last ten years.
“They identified five other licences, all for sodium fluoride, issued in July 2004, September 2005, March 2007, February 2009 and May 2010 (for, respectively, 50kg, 2,000kg, 50kg, 2,000kg and 50kg).
“These licences all predate the conflict in Syria. They were issued to two UK exporters for despatch to two Syrian companies.
“I am confident that each application was properly assessed to determine end use and that the exports were for legitimate commercial purposes, namely cosmetics and healthcare products.
“The volumes of sodium fluoride covered by these licences are consistent with commercial use.
“I want to assure you there is no evidence that exports of chemicals from the UK have been deployed in Syrian weapons programmes and I have determined that there has been no breach of controls or international obligations.
“The government remains confident that UK export controls continue to be among the most stringent in the world.”
However, CAEC chairman Sir John Stanley wrote to Mr Cable asking for details of the products which were manufactured using the chemical and the names of the companies which were involved in the deals in Britain and Syria.
Big names pen intervention plea
Political grandees have written to the three main party leaders saying the UK should not abandon its commitment to humanitarian intervention following the government’s defeat in the vote on Syria.
Former Tory leader Lord Howard, former Liberal Democrat leader Lord Ashdown and former Labour cabinet minister Lord Mandelson have signed the letter, which reflects a fear among some in Westminster that the vote could signal a change in the way Britain acts on the global stage.
The message warns that the UK must not “renounce its aspiration to engage internationally”, claiming such a step would mean rejecting the lessons learned from the atrocities in Rwanda and Bosnia.
The political heavyweights also warn against any move to reject the United Nations doctrine of responsibility to protect civilians, even if that involves military action. They said: “Whatever one’s views on the vote, this must not be the point in British history at which we reach a fork in the road and choose to abandon such an important notion of collective global responsibility.
“The UK has been a long-time champion of this emerging norm of international law that states that when a government is unable or unwilling to protect its own civilian population from genocide, war crimes and crimes against humanity the international community has a responsibility and obligation to respond.
“Most often, the response should be one of diplomacy and negotiation. In certain cases, we must be able and willing to intervene militarily.
“For some of us, Syria was one such case. For others, a persuasive and credible case has not been made.”
The letter was also signed by senior Tories Richard Ottaway, the Foreign Affairs Select Committee chairman, Joint Intelligence Committee chairman and former foreign secretary Sir Malcolm Rifkind and former international development secretary Andrew Mitchell.
Senior Labour figures who signed the letter include former defence secretary Lord Hutton, former Nato secretary general Lord Robertson and former home secretaries David Bunkett and Jacqui Smith.