Damascus, Syria ? The U.S. ambassador to Syria was called back to Washington on Tuesday as anger swelled against Damascus following the assassination of former Lebanese Prime Minister Rafik Hariri.

In Beirut, where Hariri was killed by a massive car bomb Monday, livid mourners spilled into the streets, cursing Syria while Quranic verse filled the air. Mobs attacked Syrian laborers in southern Lebanon and burned tires outside a Syrian government building in Beirut. The Lebanese army went on alert for further violence, and barricaded trucks with beds full of soldiers appeared on street corners throughout Beirut.

Suspicion for the explosion has landed squarely on Syria, an embattled nation that’s now poised to pay a diplomatic and political price for the billionaire construction magnate’s death.

Syria’s ambassador to the United States, Imad Moustapha, denied involvement Tuesday in an interview on CNN. “Syria has nothing to benefit from what has happened,” he said.

But the assassination is expected to harden international resolve to force Syrian troops out of Lebanon and also to strip Syria of support from sometime defenders including France and Jordan. Damascus has for months ignored a United Nations Security Council mandate to withdraw its forces from neighboring Lebanon.

At the United Nations, the Security Council condemned the assassination and asked Secretary-General Kofi Annan to investigate its cause. The United States asked the council to consider measures to punish the perpetrators, an American official said, a move that could lead to a demand that Syria remove its troops.

Anne W. Patterson, the acting U.S. ambassador to the United Nations, said, “Syria has got to get out of Lebanon. … I think that message has been very specific and it’s time for Syria to listen to that now.”

U.S. officials did not specifically blame Syria for the killing, but Patterson said it was a direct result of Syria’s presence in Lebanon. “This is only the most recent and frankly the most horrific demonstration of the effects of that foreign interference,” she said.

Debris and a large crater mark the site of a bomb blast in Beirut, Lebanon. Monday's explosion killed former Prime Minister Rafik Hariri, and police said at least 14 people died and about 120 people were injured in the bombing.