Syria's allies in Russia called for urgent talks between Damascus and the opposition, saying an attack by Syrian renegade troops on a government building looks like the start of a civil war.
President Bashar Assad is facing severe international isolation stemming from his crackdown on an 8-month-old uprising, which the UN estimates has killed 3,500 people. The Arab League suspended Damascus on Wednesday and threatened economic sanctions if the violence continues.
"This is all looking very much like a civil war," Russian Foreign Minister Sergey Lavrov told reporters in Moscow, referring to a pre-dawn attack on Wednesday by the Free Syrian Army, a group of army defectors determined to bring down the regime.
Wednesday's attack could not be independently confirmed, and the Free Syrian Army released no details about the fighting or possible casualties.
The army defectors reportedly fired machine guns and rockets at an Air Force Intelligence base just outside Damascus — a brazen attack that sent a strong signal the popular uprising could descend into an armed conflict.
Lavrov urged Syrian and opposition forces alike to cease violence and negotiate, but he reserved his harshest words for the opposition.
"It is not a secret that along with the peaceful demonstrators, whose strivings and demands we support, there is more and more participation from groups of armed people who have an entirely different agenda from reform and democracy in Syria," he said. "Their agenda concerns ethnic and tribal interests, and these people have received and are continuing to receive weapons in growing amounts from neighboring countries, and they don't particularly hide it.
"Weapons are being smuggled in through Lebanon, Iraq, Afghanistan, Jordan, and if the opposition uses such methods, this will lead to a full-scale civil war," Lavrov said.
On Monday, the Russian foreign minister suggested Western countries were exacerbating problems in Syria by inciting the opposition.
Lavrov met on Tuesday in Moscow with the head of the opposition Syrian National Council, Burhan Ghalioun, in a failed attempt to persuade him to negotiate with Assad's regime.
Even as Assad was losing allies in quick succession, Russia and China kept up their long-standing ties with Damascus. In October they vetoed a UN Security Council resolution that threatened sanctions against Syria.
But on Thursday, Chinese Foreign Ministry spokesman Liu Weimin appeared to suggest Beijing might support a resolution in the future.
"It depends on whether these actions will help to resolve the tensions in Syria and facilitate the resolution of disputes through political dialogue," he said.
He called on both sides in the conflict to work together.
The crisis appears to be spiraling out Assad's control, however, as attacks by army defectors increase and world leaders look at possibilities for a Syrian regime without him.
Germany, Britain and France are pressing for a UN resolution that would strongly condemn Syria's human rights violations. The three European countries decided to move ahead with the General Assembly resolution after the Arab League confirmed its suspension.
"We hope it will show Assad just how isolated he is," Germany's UN Ambassador Peter Wittig said of the resolution.
Turkey's prime minister, Recep Tayyip Erdogan, said Thursday the world must urgently "hear screams" from Syria and do something to stop the bloodshed.
He said the uprising in Libya got far more worldwide attention because Libya has more oil.
"The lack of reaction to massacres in Syria was causing irreparable wounds in the conscience of humanity," he said.
The growing calls for Assad's ouster are a severe blow to a family dynasty that has ruled Syria for four decades — and any change to the leadership could transform some of the most enduring alliances in the Middle East and beyond.
Syria's tie to Iran is among the most important relationships in the Middle East, providing Tehran with a foothold on Israel's border and a critical conduit to Tehran-backed Hezbollah in Lebanon and the Palestinian Hamas in Gaza.
Also Thursday, Syrian Observatory for Human Rights and the Local Coordination Committees, an activist coalition, said five civilians were killed during raids by security forces in central, eastern and northern Syria, including a 9-year-old girl.
In addition, the LCC said four defected soldiers were killed in Sashl al-Ghab in the suburbs of Hama. In a Facebook posting, the Free Syrian Army claimed responsibility for striking at a military checkpoint in the area, saying it killed four members of the security forces and wounded many others. It also said four members of the Free Syrian Army, including a lieutenant colonel, died in the clashes.