The opposition Syrian National Coalition is due to discuss whether it will attend a peace summit in Geneva next week, after the Syrian government said it had offered a limited ceasefire and prisoner swap in anticipation of talks.
The SNC was due to meet on Saturday in Istanbul, a day after failing to decide whether it would attend the UN-backed talks, set to start on January 22.
The meeting comes after a flurry of diplomatic activity. On Friday, the Syrian foreign minister, Walid al-Muallem, announced he had handed Russia plans for a ceasefire in Aleppo, and was ready to exchange lists with rebel forces on a possible prisoner swap.
Muallem said: "The desires and aspirations of the Syrian people are important to us," he said. "I believe the coalition will arrive at a decision for the good of the Syrian people".
The US secretary of state, John Kerry, however called the regime's offer a diversion from the aim of the talks - installing a new government.
"I'm not particularly surprised that he is trying to divert this. He's been doing this for months, trying to make himself the protector of Syria against extremists," Kerry said of the Syrian president, Bashar al-Assad.
Kerry slammed alleged comments from the Syrian regime that the Geneva II peace talks were to discuss ways to combat the rise of terrorist groups plaguing the country as "revisionism".
Kerry also reiterated the point that talks would only be successful if the Syrian regime accepted a transitional government.
"I believe, as we begin to get to Geneva and begin to get into this process, that it will become clear that there is no political solution whatsoever if Assad is not discussing a transition and if he thinks he's going to be part of that future. It's not going to happen," Kerry said.
Washington and Moscow have been trying to negotiate confidence-building measures to force the two sides to the table in Geneva. The SNC has previously demanded the resignation of Assad before it commits to talks.
Fighting continues in Syria as diplomats and politicians attempt to agree on the peace talks. The Syrian Media Centre group reported heavy government shelling across parts of Damascus this morning, including in Qaboun and Qalamoun.
It also reported that barrel bombs had been dropped on Zabadani, a suburb of Damascus, by government helicopters, causing significant damage to residential areas. The number of casualties is still unknown.
In Northern Aleppo, the Islamic State of Iraq and the Levant (ISIL) attacked the rival rebel group, the Islamic Front, with a car bomb, killing 13. It also attacked rival rebels in the east of the district, killing four.