The Arab League said Sunday it had agreed to open contacts with Syria's opposition and ask the United Nations to form a joint peacekeeping force to the nation, moves swiftly denounced by Syria.
In Lebanon meanwhile, refugees from the Syrian city of Homs which is besieged by President Bashar al-Assad's troops, gave graphic accounts of what they had endured.
Arab League diplomats "will open channels of communication with the Syrian opposition and offer full political and financial support, urging (the opposition) to unify its ranks," said a League statement obtained by AFP.
They would also "ask the UN Security Council to issue a decision on the formation of a joint UN-Arab peacekeeping force to oversee the implementation of a ceasefire."
After marathon talks in Cairo, the 22-member bloc announced a formal end of its own observer mission to Syria, suspended last month because of an upsurge in violence.
Only Algeria and Lebanon expressed reservations about the resolution, an Arab League official said.
Syria's ambassador to Cairo denounced the League moves.
"The Syrian Arab Republic categorically rejects the decisions of the Arab League," which "reflects the hysteria of these governments" after failing to get foreign intervention at the UN Security Council, Yusef Ahmed said in a statement.
Burhan Ghalioun, leader of the opposition umbrella grouping the Syrian National Council, told Al-Jazeera television he welcomed the moves as "a first step" towards the fall of the regime.
On the ground, the Syrian Observatory for Human Rights reported that at least 39 civilians had been killed on Sunday, many in a relentless assault by President Bashar al-Assad's forces on the central protest city of Homs.
Most died in Baba Amr, a rebel stronghold armed forces have targeted for more than a week, killing at least 500 people.
The Observatory also reported fierce clashes on the northern edge of nearby Rastan, where a woman was killed when a rocket hit her home.
Elsewhere, snipers killed a child in Daraa, cradle of the 11-month uprising against Assad's regime.
As the military pressed its onslaught on Homs, refugees who had fled the city acros the border to Lebanon told of the horrors they had witnessed.
"The army of Bashar al-Assad destroyed our homes," Abu Ibrahim told AFP.
"Before, we were bombarded by mortars or rocket-propelled grenades, but now they are using tanks and helicopters."
Ibrahim said his 10-year-old daughter Nada had refused food since seeing dead bodies littering the streets of the besieged city.
Signup to our newsletter and follow us on Facebook and Twitter!
The Syrian Arab Red Crescent and International Committee of the Red Cross said their "volunteers are distributing food, medical supplies, blankets, and hygiene consumables to thousands of people" in Homs.
"The population, particularly the wounded and sick, are bearing the brunt of the violence," the ICRC's Marianne Gasser said in a statement.
UN chief Ban Ki-moon had broached the idea of a joint Arab-UN mission this month as he bemoaned the Security Council's failure to agree a resolution on Syria in the face of Chinese and Russian opposition.
The Arab League has already put forward a plan for Assad to transfer power to his deputy and for a government of national unity to be formed ahead of elections.
On Sunday, Syrian government newspaper Ath-Thawra accused Arab nations of being in the pay of Western powers, accusations echoed by Damascus's ambassador to Cairo.
The League's decision to back the opposition and call for joint UN-Arab peacekeepers showed it was "hostage to the governments of (certain) Arab countries headed by Qatar and Saudi Arabia," working in collaboration with the West, Ahmed said.
Arab and western states will launch a bid at the UN General Assembly this week to put pressure on Assad after Saudi Arabia and Qatar drew up a resolution backing the League plan to end the crackdown.
The move follows the Russian and Chinese veto of virtually the same resolution in the Security Council eight days ago. Moscow and Beijing are expected to oppose the new text.
However, no one can veto resolutions in the 193-nation General Assembly, which carry less weight.
The United States and its allies are bringing "pressure to bear" on Syria, White House chief of Staff Jacob Lew said.
"Since August, we have been bringing pressure to bear," Lew told Fox News.
"There's a lot of pressure being brought to bear and I think that it's been effective and it will be effective. This regime will come to an end," Lew said.
Syrian state television on Sunday showed an official funeral for the 28 people authorities say were killed in twin car bombs in the northern city of Aleppo on Friday.
The deputy foreign minister accused Arab and Western countries, which he did not name, of supporting the "terrorists" who carried out the attacks.
Damascus frequently blames foreign-backed "armed terrorist gangs" for the violence.
The rebel Free Syrian Army had accused the regime of launching the Aleppo attacks "to steer attention away from what it is doing in Homs, Zabadani and elsewhere."
A US media report citing unnamed American officials said Al-Qaeda's Iraqi branch was likely to have carried out the bombings, along with attacks in Damascus in December and January.
Rights groups say more than 6,000 people have died since protests began in Syria in March last year, inspired by similar movements in Tunisia, Egypt and Libya.