Syria has pledged to withdraw all military units from towns by April 10 to pave the way for a ceasefire with rebels two days later, though Western envoys were skeptical on Monday about Damascus' intent to halt its year-long assault on opponents.
The U.N.-Arab League peace envoy Kofi Annan briefed the U.N. Security Council on the deadline behind closed doors. He told them there had been no reduction in violence so far, but urged them to consider an observer mission nevertheless in light of Syria's acceptance of the April 10 deadline, diplomats said.
Washington's U.N. Ambassador Susan Rice, president of the 15-nation Security Council this month, said some council members "expressed concern that the government of Syria not use the next days to intensify the violence and expressed some skepticism about the bona fides of the government in this regard."
Syrian President Bashar al-Assad has repeatedly promised to stop his campaign against anti-government activists, which has brought the country to the brink of civil war, but has not kept his word.
Annan told the council that the Syrian foreign minister sent him a letter on Sunday saying the government accepted his proposal - the first time the Syrians have accepted a specific deadline.
"The Syrians have told us they have put a plan in place for withdrawing their army units from populated zones and surrounding areas. This plan ... will be completed by April 10," Annan's spokesman Ahmad Fawzi said in Geneva.
"If we are able to verify this has happened on the 10th, then the clock starts ticking on the cessation of hostilities, by the opposition as well. We expect both sides to cease hostilities within 48 hours," he told Reuters.
Whether or not Assad plans to comply with the deadline, Western diplomats said Syria's acceptance of it might not have come if the Russians had not urged him to accept it.
Russian Foreign Minister Sergei Lavrov said it was up to Damascus to make the first move towards a ceasefire as called for in Annan's plan, suggesting a shift in Russia's public position. Until recently Moscow had been saying Syria's army and opposition fighters should halt fighting simultaneously.
"The Syrian government must take the first step and begin the troops' pullout - that is written in the Kofi Annan plan and we support this obligation," Interfax quoted Lavrov as saying.
Russia and China have vetoed two council resolutions condemning Assad for turning the army on civilians.
Annan met Assad in Damascus on March 10 and presented him with a six-point plan calling for the military pullout. His spokesman said a week ago that Assad had accepted the terms, adding that "the deadline is now."
Syria's Ambassador to the United Nations, Bashar Ja'afari, confirmed to reporters that Damascus had accepted the April 10 deadline but said the government wants the opposition on board.
"The Syrian government is committed but we are expecting Mr. Kofi Annan and some parties in the Security Council also to get the same kind of commitments from the (opposition)," he said. "A plan wouldn't be successful unless everybody is committed."
Diplomats said the Security Council might try to issue a statement in the coming days formally endorsing the deadline. Rice said Annan told the council he would have liked an earlier deadline and urged Damascus to "start immediately and to ensure that forces move no further into population centers."
One diplomat said Annan confirmed to council members that there had been "no progress on the ground" toward halting the violence and there are daily reports of army shelling and battles with rebels of the Free Syrian Army.
"Today doesn't feel much different from yesterday or the day before, or the day before that," opposition activist Waleed Fares said from inside Homs. "Shelling and killing."
The British-based Syrian Observatory for Human Rights, which collates information from around Syria, reported 35 people killed on Monday, including eight soldiers and nine rebels, after 70 deaths on Sunday.
Ten civilians were killed on Monday in the central province of Homs. In Syria's second city of Aleppo, a bomb blast at a kiosk killed the owner, an Assad supporter, it said. At least five people were killed and eight wounded in army bombardments of villages in northern Idlib province, which borders Turkey.
Turkish officials said about 400 refugees a day were crossing the border. More than 40,000 Syrians have taken refuge in neighbouring countries since the unrest broke out a year ago, according to U.N. figures.
The president of the International Committee of the Red Cross arrived in Damascus to press for a daily two-hour ceasefire to evacuate wounded and deliver vital supplies to civilians, a proposal first made in February.
Despite the lack of progress, Annan urged council members to "begin consideration of deployment of an observer mission with a broad and flexible mandate," a diplomat said.
U.N. peacekeepers are already planning for a ceasefire monitoring mission that would have 200 to 250 unarmed observers. It would require a Security Council resolution.
NATO Secretary-General Anders Fogh Rasmussen repeated that the Western allies have "no intention whatsoever to intervene in Syria." He said he did not believe providing weapons would help.
Saudi Arabia and Qatar favor providing arms to the rebels, but most Arab and Western states oppose that.
Ja'afari blasted the support the rebels have received from abroad: "This is a violation and a declaration of war against the sovereignty of Syria."
Rebel leaders have said they will stop shooting if the Syrian army pulls its heavy weaponry out of the cities, but the Assad government has insisted it must maintain security in urban areas and there has been no sign of tanks, armour or artillery moving out.
The United Nations estimates Syrian soldiers and security forces have killed more than 9,000 people over the past 12 months. Damascus says the rebels have killed 3,000 troops and police.
Assad blames the unrest on foreign-backed "terrorists" and has put forward his own reform program, which his domestic foes and international opponents have dismissed.