GENEVA The United Nations' human rights chief urged countries on Wednesday not to supply Syria with weapons and to press both sides to find a political end to the war, to prevent more massacres and the threat to regional stability.
"If the current situation persists, or deteriorates further, increased inter-communal massacres are a certainty, rather than a risk," Navi Pillay told the U.N. Human Rights Council.
Referring to efforts to convene a peace conference in Geneva in coming weeks, she said: "This is an extremely important opportunity for states with influence to pull the parties back from the brink of catastrophe ... The flow of arms must stop and the process of national dialogue must begin now."
Pillay spoke after the European Union decided to let an EU arms embargo on Syria expire and Russia said it would deliver an advanced S-300 air defence system to the Damascus government despite U.S., French and Israeli objections.
France and Britain, the EU's top military powers and most ardent advocates of scrapping the embargo, said they had not yet decided to arm Syrian rebels, but wanted to put President Bashar al-Assad under pressure to negotiate.
Diplomats said Pillay's appeal to halt the flow of arms and foreign fighters was also aimed at Gulf states, including Qatar, which backs the rebels, and Iran, Syria's ally in the 26-month-old conflict that has taken the lives of at least 80,000 people.
The council discussed the intensified fighting, particularly an offensive by government forces on the rebel-held town of Qusair.
"The assault on Qusair is the latest regime attempt to use sectarian-driven war to divide the Syrian people," U.S. Ambassador Eileen Chamberlain Donahoe said, blaming airstrikes and artillery bombardment for killing more than 183 civilians.
A dramatic increase in the role of Iran-backed Hezbollah militants backing Syrian government forces was inflaming regional tensions and inciting instability in Lebanon, she said.
Russian Foreign Minister Sergei Lavrov criticised a U.S.-backed draft resolution before the council condemning the Syrian government, saying it was "odious" and would undermine efforts to convene an international peace conference.
The draft resolution, to be voted on later on Wednesday by the 47-member forum, was amended overnight after negotiations to include condemnation of all violence, including "terrorist acts".
Russian ambassador Alexey Borodavkin said that the session was "untimely, counterproductive and likely to complicate the launch of the peace process in Syria."
Syrian Ambassador Faysal Khabbaz Hamoui accused Qatar and Turkey of being "major parties in the bloodshed in Syria" by helping to "recruit jihadist extremists" from more than 40 countries.
"The draft resolution today is biased and politically motivated ... It is far from the truth," he said.
Turkey's ambassador Oguz Demiralp said the debate was urgent as up to 40 shells a minute were reported to be falling on Qusair.
"The Syrian regime is pursuing a sectarian-driven war to divide the Syrian people. It is pursuing a blatant policy of ethnic cleansing with no sign of shame," he said.
(Additional reporting by Tom Miles; Editing by Robin Pomeroy)