Updated

Syrian allies China and Russia expressed serious concern Thursday over the spiraling crisis in Syria and called for immediate talks as pressure mounted on President Bashar Assad to end the deadly crackdown on dissent.

Assad is facing severe international isolation stemming from his crackdown on an 8-month-old uprising, which the U.N. estimates has killed 3,500 people. The Arab League suspended Damascus on Wednesday and threatened economic sanctions if the violence continues.

The call came for urgent talks between Damascus and the opposition, saying an attack by Syrian renegade troops on a government building the previous day looks like the start of a civil war.

Assad is facing severe international isolation stemming from his crackdown on an 8-month-old uprising, which the U.N. 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 Sergei 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.

The army defectors 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.

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 U.N. Security Council resolution that threatened sanctions against Syria.

But on Thursday, Chinese Foreign Ministry spokesman Liu Weimin appeared to suggest China 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 of 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 U.N. 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 U.N. 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 about 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 the Iranians with a foothold on Israel's border and a critical conduit to Tehran-backed Hezbollah in Lebanon and the Palestinian Hamas in Gaza.