The Obama administration says the U.N. Security Council “must” intervene in Syria's escalating violence by sending a message that President Bashar al-Assad's crackdown on a 10-month opposition uprising is a threat to global peace and security.

In a statement Monday, U.S. Secretary of State Hillary Clinton said Washington strongly condemns what it calls “violent and brutal” Syrian government attacks that have killed hundreds of civilians in the past few days. She said she will attend a U.N. Security Council session on Tuesday to urge that the world body support an Arab League plan for Mr. Assad to step aside as a way of resolving the crisis.

European leaders joined the U.S. in urging the Council to take steps to end the repression in Syria. British Prime Minister David Cameron called the situation there “appalling” and said Syria should back international efforts aimed at securing Mr. Assad's resignation.

Syrian opposition activists said government troops re-took control of several Damascus suburbs Monday in heavy fighting, with rebels leading the revolt against Mr. Assad's 11-year autocratic rule. The activists said pro-Assad forces drove the Free Syrian Army forces out of some eastern districts closest to central Damascus, before moving into neighboring areas and engaging in more deadly street battles.

Activists also reported fighting between government troops and rebels in the central province of Homs. They said Monday's violence across Syria killed at least 28 people, mostly civilians.

The foreign ministers of France and Britain also will attend Tuesday's Security Council session to show support for the Arab League initiative, which Damascus has rejected as a violation of its sovereignty. Western powers and Arab nations have been working on a draft resolution endorsing the plan.

But Russian Deputy Foreign Minister Gennady Gatilov said Moscow “cannot support” the proposed resolution because it is biased against Mr. Assad's government, a long-time Russian ally and buyer of Russian military supplies.

In an interview with Russia's Interfax news agency, Gatilov also said the document “leaves open the possibility of intervention” in Syrian affairs, something Moscow has vowed to oppose. Russia joined China last October in vetoing a Western-backed resolution that would have condemned the Syrian government's crackdown on the uprising.

Russia said Monday it persuaded the Syrian government to send a delegation to Moscow for proposed peace talks with the Syrian opposition. But members of the opposition Syrian National Council quickly rejected the idea. In a statement emailed to VOA, SNC member Ausama Monajed said the group “does not negotiate with terrorists.”

White House spokesman Jay Carney said Monday that Washington supports Russian efforts to reach a political solution to Syria's violence. But he also said the U.N. Security Council must not allow the Assad government to reject Arab League peace proposals while continuing to “assault” the Syrian people.

U.S. Ambassador to the United Nations Susan Rice said the Moroccan-sponsored resolution backed by the West does not threaten sanctions or the use of force against the Syrian government, as some critics have alleged. A French diplomatic source told Western news agencies that at least 10 Council members support the draft.

The Syrian government accuses armed terrorists of driving the anti-Assad revolt and killing 2,000 security personnel. The United Nations estimated the death toll from the unrest at 5,400 earlier this month, before it stopped updating the figure because of difficulties in obtaining information.