The six Gulf countries, which have spearheaded regional condemnation of President Bashar al-Assad's regime, began talks in the Egyptian capital ahead of an Arab League gathering.
As the meeting got under way, the Syrian Observatory for Human Rights reported army shelling killed at least four civilians in the protest city of Homs, including three in the rebel stronghold of Baba Amr.
The Observatory's Rami Abdel Rahman told AFP that another 30 tanks and armed personnel carriers were on the way to Homs, which armed forces have pounded for more than week, killing at least 500 people, according to activists.
On the eve of the Cairo talks, the Syrian National Council said Arab recognition of the opposition umbrella group was imminent. Arab League foreign ministers were also expected to consider proposals for an observer mission, withdrawn last month because of an upsurge in violence, to be returned with UN reinforcement.
UN chief Ban Ki-moon broached the idea this month as he bemoaned the Security Council's failure to agree a resolution on the crisis in the face of Chinese and Russian opposition. The 22-member League has put forward a plan for Assad to hand power to his deputy and for the formation of a unity government ahead of polls.
The Gulf monarchies have ordered their envoys home from Syria and expelled Damascus's ambassadors, joining mounting pressure on Assad over the killings of civilians.
In a tit-for-tat move, the Syrian government said it has asked Tunisia and Libya to close their embassies in Damascus. Government newspaper Ath-Thawra accused the Arab nations of being in the pay of Western powers.
"There will probably be no surprises because the orders have already been sent. They do not decide anything; they just carry out orders. They have done that in the past and they will do it today," it said referring to the Cairo meetings.
On Saturday, tensions escalated in Aleppo as Assad's forces stepped up security a day after twin car bombs killed 28 people and wounded 235, activists said. State media blamed "terrorists," but the rebel Free Syrian Army accused the regime of launching the 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 Aleppo bombings, along with attacks on Damascus in December and January. The attacks appeared to verify Assad's charges of Al-Qaeda involvement in the uprising against his 11-year rule, said the McClatchy Newspapers chain.
Iraq's deputy interior minister said jihadists were moving from Iraq to Syria, as are weapons being sent to Assad's opponents. "We have intelligence information that a number of Iraqi jihadists went to Syria," Adnan al-Assadi told AFP, adding "weapons smuggling is still ongoing."
And Al-Qaeda leader Ayman al-Zawahiri voiced his support for Syria's uprising in a new video posted on jihadist Internet forums, US monitors SITE Intelligence said. "I appeal to every Muslim and every free, honourable one in Turkey, Iraq, Jordan, and Lebanon, to rise to help his brothers in Syria with all that he can," he was quoted as saying.
Forty-five people were killed nationwide Saturday, mostly civilians, said the Britain-based Observatory.
Homs activist Hadi Abdullah accused policemen and soldiers of pillaging Inshaat district. "They are stealing computers, television sets... and even blankets." Security forces also advanced into Zabadani, said the Observatory, adding three civilians were killed in the town located between Damascus and the Lebanese border.
In Lebanon, a 17-year-old girl was among three people killed and 23 were wounded in clashes Saturday between Sunnis hostile to Syria's regime and Alawites who support it, a security official said.
Ten of the wounded were Lebanese soldiers.
The rival factions in Tripoli, in northern Lebanon, fired guns and rocket-propelled grenades in the bloodiest clashes since June, when six people died in the wake of demonstrations against Syria's government.
A general was assassinated Saturday in Damascus, state media said. If confirmed, it would be one of the most brazen attacks on top brass in the capital since the uprising erupted in March last year.