The United States has expressed reservations about the credibility of the Syrian government's promise to observe a cease-fire beginning at 6 a.m. local time on April 12.
"Fighting is still raging as we speak, reflecting what has been an intensification of the violence that the Syrian government has pursued since April 1 when it committed to cease all hostile actions by yesterday," U.S. Ambassador to the UN Susan Rice told reporters in New York
"Its commitments, therefore have little if any credibility -- and I am, let me clarify, speaking in my national capacity -- given that track record."
In Washington, U.S. Secretary of State Hillary Clinton told a meeting of G8 country foreign ministers that the United States was "alarmed" at the ongoing violence and concerned about the problems UN/Arab League envoy Kofi Annan has encountered as Damascus fails to honor the cease-fire.
She said the ministers would be discussing the matter during their afternoon talks:
"We will look for ways that we can, together, try to bring about a peaceful resolution of the current situation and a political transition for the sake of the Syrian people," Clinton said.
Annan said earlier on April 11 that Damascus had informed him it will stop all military action on Thursday.
But the Syrian government said it reserved the right to respond to any attacks by rebel forces.
Annan's spokesman, Ahmad Fawzi, said the envoy would continue to work with Damascus and the opposition to ensure the implementation of the cease-fire plan.
Under Annan's plan, the Syrian government was originally to have begun pulling its forces out of cities on April 10 before observing a full cease-fire by April 12.
But the Syrian government failed to completely pull back and Syrian activists say government forces continue to use heavy weapons to attack opposition neighborhoods.
Activists say attacks by government forces killed at least 12 people on April 11.
Earlier on April 11, Annan appealed to Syria's key ally, Iran, to support his plan to end the violence in Syria, saying that "any further militarization of the conflict would be disastrous."
"If we stick together, support this process, and work with the Syrians, we should be able to find the solution," Annan told reporters.
"And I'm grateful for the support of Iran, given its special relations with Syria, and I believe Iran can be part of the solution."
Annan was speaking after meeting with Iranian Foreign Minister Ali Akbar Salehi in Tehran. Salehi said Syrian President Bashar al-Assad should stay in power regardless of the course of the Syrian conflict.
Iran has supported Assad's government since the outbreak of unrest last year, but denies Western claims that it supplied Syria with weapons to crack down on the opposition.
Russia said on April 11 that the Syrian government's pledge to stop army operations on April 12 means the opposition must now also honor the cease-fire.
U.S. Secretary of State Hillary Clinton is due to hold talks on Syria with her Russian counterpart, Sergei Lavrov, in Washington later in the day.
Meanwhile, a Jordanian Interior Ministry official told AP privately on April 11 that the country now had 95,000 Syrian refugees who fled the conflict at home.
Another 25,000 refugees from Syria are in Turkey.
More than 9,000 people have been killed in Syria since a pro-democracy uprising started in March 2011, according to the UN.
With reporting by dpa, AP, and AFP