Russia acknowledged on Saturday that Syrian President Bashar al-Assad will not be persuaded to quit but insisted there is still a chance of finding a political solution to the 21-month conflict.
International peace envoy Lakhdar Brahimi warned Syria was facing a choice between "hell or the political process" after talks with Russian Foreign Minister Sergei Lavrov on his end-of-year bid to accelerate moves to halt a conflict that monitors say has now killed more than 45,000 people.
The talks came amid emerging signs that Russia was beginning to distance itself from Assad's government and urgent efforts by Brahimi to resurrect a failed peace initiative that world powers agreed to in Geneva in June.
"It is really indispensible that the conflict finishes in 2013 and really the beginning of 2013," the envoy said.
Lavrov said both he and Brahimi agreed there was hope for a solution as long as world powers put pressure on both sides.
"The confrontation is escalating. But we agree the chance for a political solution remains," he said.
Moscow has been under intense pressure to urge the leadership of its last Middle East ally to accept a face-saving agreement that would see the rebels assume gradual command as the fighting reaches Damascus itself.
Yet analysts have questioned the actual sway the Kremlin has over Assad, and Lavrov appeared to betray a hint of frustration when revealing that Assad had this week told Brahimi that he does not intend to leave.
"Regarding Bashar al-Assad, he repeatedly said, both publically and in private... that he is not planning to leave, that he will remain in his post," Lavrov said.
"There is no possibility to change this position."
Brahimi painted a stark picture of Syrian neighbours Jordan and Lebanon being overrun by a million refugees should heavy fighting for the seat of power break out in Syria's five-million-strong capital.
Signup to our newsletter and follow us on Facebook and Twitter!
If this fighting "develops into something uglier... (refugees) can go to only two places -- Lebanon and Jordan.
"So if the alternative is hell or the political process, we have all of us got to work ceaselessly for a political process," Brahimi said.
Lavrov echoed that message by warning that Syria threatened to dissolve into a failed state similar to Somalia -- a nation overrun by warlords and jihadists.
"Syria must have a stable political process. That is one alternative," the Russian minister said.
"The other alternative is the Somalisation of Syria -- and you can only imagine the consequences of that."
Brahimi's trip came amid a flurry of diplomatic activity in Moscow that saw Russia issue an invitation to talks to the armed opposition National Coalition -- recognised by Western governments as sole legitimate representative of the Syrian people.
The invite was rebuffed by National Coalition chief Ahmed Moaz al-Khatib, drawing an angry response from Lavrov.
"I understand that Mr. Khatib is not very fluent in politics and maybe he could benefit by hearing our position not from the media... but directly from us," he said.
On the ground, at least 153 killed were killed in violence on Saturday, among them 76 civilians, the Syrian Observatory for Human Rights said.
Eight children were among at least 17 people killed in air strikes on the suburbs of Damascus, the Britain-based watchdog added.
Egyptian President Mohamed Morsi insisted: "There is no place for the current regime in a future Syria."
Lebanon seized a consignment of mortars and machineguns near its border with Syria, a security source said, without confirming that they were intended to be delivered to the rebels.