Annan's description of events was clear, he continued. "Not only has the use of heavy weapons not ended, not only have releases of political prisoners been minimal compared with the dimensions of the crackdown, not only is Damascus now attacking its neighbors, but what was presented as a withdrawal is in fact only a thinly disguised redeployment."

In unusually blunt language, he took aim at the Syrian president. "Bashar al-Assad has lied to Kofi Annan, who enjoys the international community's full support. I regret it all the more in that the opposition was prepared to do its part, provided that Damascus respected its prior commitments."

Sheikh Anas Airout, a senior member of the Syrian National Council, said Annan did not get an agreement from the opposition body but that the Free Syrian Army, a main armed opposition group composed primarily of defected soldiers, committed to abide by the cease-fire as long as the regime stopped its attacks.

Activists in three separate provinces said the Free Syrian Army had held to a 48-hour cease-fire starting Tuesday morning to allow al-Assad the opportunity to withdraw his soldiers.

But with the regime and rebel fighters both refusing to back down until the other side does, prospects faded for an end to the fighting. And the bloodshed continued unabated in cities like Homs, Idlib and suburban Aleppo and Damascus.

Syrian activists had angry words for Annan, saying the peace process was just giving al-Assad more time to kill.

Shells rained down on the western city of Homs, activists said, Rockets destroyed a civilian hospital in the suburbs, and tanks rolled down streets.

"What Annan said is funny and sad at the same time. While rockets and shells are raining down on us, he is talking about talk," activist Abu el Fadaa said. "If these are the requirements of negotiations, we don't want negotiation after every negotiation."

And in the northern province of Aleppo, al-Assad's forces shelled the town of Maarei from its outskirts, the opposition Syrian Observatory for Human Rights said.

"So far, we have not documented until now any withdrawal or movements by the Syrian security forces on the ground, despite the calm that is seen in most parts (of the country)," the group said.

Susan Rice, the U.S. ambassador to the United Nations, said the Security Council members were "unified in their grave concern that this deadline has passed and the violence has not only continued but, over the last 10 days, has intensified."

Early last week, the Syrian government agreed to Tuesday's deadline to withdraw troops. Annan's six-point peace plan also calls for a halt in violence by both sides and a Syrian-led political process to end the crisis.

CNN cannot independently verify reports of violence and deaths as the government has severely restricted access by international media.

The United Nations estimates that the violence in Syria has killed at least 9,000 people. The LCC puts the toll at more than 11,000.

The Syrian regime has consistently blamed the violence in the country on "armed terrorist groups," but many world leaders have said the government is lethally cracking down on dissidents seeking democracy and an ouster of al-Assad, whose family has ruled Syria for 42 years.

Rebels, including defectors from al-Assad's forces, have taken up arms, but they are outnumbered by better equipped government forces.

On Monday, the crisis spilled over into Turkey, resulting in casualties at a refugee camp.

Turkish Prime Minister Recep Tayyip Erdogan said Tuesday that Syria committed a border violation and that officials were "conducting diplomacy with regional countries and will soon take the necessary steps," Turkey's semi-official Anadolu news agency reported.

But Erdogan said Turkey will not turn its back on Syrian refugees.

"We cannot shut down our doors to these people," Erdogan said, according to Anadolu. "If the doors are shut down, they will be toasted."