Foreign ministers from more than 70 Western and Arab countries are meeting in Istanbul to explore ways to step up pressure on the Syrian regime and bolster the opposition.
The BBC reports the second so-called Friends of Syria meeting follows opposition calls for rebel fighters to be armed.
The opposition says President Bashar al-Assad's backing of a UN-Arab League peace plan is a ploy to win time.
The Syrian government, meanwhile, has declared victory over rebel fighters.
Activists say at least 25 people died in violence on Saturday, with security forces continuing bombardments in the city of Homs and other areas.
The foreign ministers meeting in Istanbul, who include US Secretary of State Hillary Clinton, are expected to maintain diplomatic pressure on President Assad, largely by insisting that he abide by the peace plan proposed by UN-Arab League envoy Kofi Annan.
President Assad's nominal acceptance of the six-point plan has been treated with scepticism by Western and Arab governments.
The Syrian National Council head Burhan Ghalioun said he believed Mr Assad's acceptance of the peace plan was another "lie and a manoeuvre" to gain time.