The head of the suspended Arab League observer mission to Syria has resigned as League foreign ministers meet to decide their next move in the crisis.
League Secretary General Nabil al-Arabi told its members in Cairo they had to move quickly to end the "vicious cycle of violence" in Syria.
The League is expected to approve Jordan ex-Foreign Minister Abdul-Illah al-Khatib as special envoy to Syria.
Meanwhile, al-Qaeda's leader has backed the Syrian uprising.
In a video message, Ayman al-Zawahiri told the opposition not to rely on the West or Arab countries for support.
Zawahiri - who took over the leadership of al-Qaeda following the death of Osama Bin Laden in May 2011 - described the Syrian government as a "cancerous regime that suffocated the free people of Syria".
He called on Muslims to offer whatever help they could.
Controversial Sudanese General Mohammed al-Dabi, who led the month-long Arab League observer mission to Syria, submitted his resignation on Sunday.
Human rights groups criticised him for his actions in Darfur, where Sudan is accused of genocide by the International Criminal Court.
The Arab League suspended its mission in Syria at the end of January, after it failed to halt the violence.
Mr Arabi said the failure of international diplomacy - referring to a UN resolution vetoed by Russia and China last weekend - had put a special responsibility on the league.
"It is imperative for us to move swiftly in all directions, to halt the vicious cycle of violence," he said in his opening words to the Arab League meeting.
Mr Arabi confirmed to the BBC that the League was discussing a call to send peacekeepers to Syria.
A draft resolution by the League is calling for an end to the observer mission and a halt to all forms of diplomatic co-operation with Syria.
Damascus has already been suspended from the Arab League.
The draft also calls for tighter economic sanctions.
Meanwhile Reuters quoted Saudi Foreign Minister Saud al-Faisal as saying the League should "open all channels of communication with the Syrian opposition and give all forms of support to it".
A delegation from the Syrian National Council (SNC), a coalition of major opposition parties, is in Cairo, hoping to be recognised by more Arab countries.
"We want the Arab countries to decide how to best co-ordinate their initiatives to take us in the same direction, in the right direction," said Basma Kadmani of the SNC.
"We have been very reassured of everyone's agendas. It is a priority to deal with the Syria issue."
The members of the Gulf Co-operation Council (GCC), which expelled Syria's ambassadors from its member countries during the week, met ahead of the Arab League talks on Sunday.
GCC and Arab League member Saudi Arabia is also circulating a draft resolution at the UN General Assembly, similar to the one vetoed in the Security Council by China and Russia.
The draft resolution "fully supports" the Arab League peace plan published last month, which called on President Bashar al-Assad to hand over power to his vice-president, and make way for the rapid formation of a national unity government including the opposition.
Saudi officials say they have not formally presented the resolution to the Assembly yet.
The General Assembly is scheduled to discuss Syria on Monday, when it will be addressed by the UN's High Commissioner for Human Rights, Navi Pillay, but no vote on the resolution is expected by then.
There is no power of veto at the General Assembly but its resolutions have no legal force, unlike those of the Security Council.
There were reports of a respite in the bombardment of Homs on Saturday night and Sunday morning, but shelling later resumed.
At least four people were killed in the Baba Amr neighbourhood of the city on Sunday, the Syrian Observatory on Human Rights said. At least 35 died on Saturday.
Activists say more than 400 people have been killed since security forces launched an assault on opposition-held areas on the city last Saturday.
Meanwhile, government forces entered the town of Zabadani, outside Damascus, after a rare ceasefire was apparently negotiated.
Human rights groups say more than 7,000 have died throughout Syria since March. The government says at least 2,000 members of the security forces have been killed combating "armed gangs and terrorists".