Syria has consolidated its chemical weapons stocks in one or two locations as rebels make advances in several parts on the country, said Russia's foreign minister.
Sergei Lavrov said Russia, which reportedly has military advisers training Syria's military, has kept close watch over its chemical arsenal.
He said the Syrian government had transferred weapons from several arsenals to just "one or two centres" to properly safeguard them. Israeli officials have also said that Syrian chemical weapons were under control "at the moment".
Lavrov announced that his country would be unwilling to offer sanctuary to President Bashar al-Assad, but would welcome offers from other nations.
"If there is anyone willing to provide him guarantees, they are welcome," he said. "We would be the first to cross ourselves and say: 'Thank God, the carnage is over.' If it indeed ends the carnage, which is far from certain.''
Russia has been rowing back since the Kremlin's Middle East envoy was quoted this month as saying the rebels could defeat Assad and that Russia was preparing for a possible evacuation of its nationals, the strongest signs yet that it was positioning itself for a post-Assad Syria.
"Listen, no one is going to win this war," Lavrov told reporters aboard a flight returning to Moscow from a Russia-European Union summit in Brussels.
Deadly car bomb
Meanwhile, in the Syrian capital, a car bomb exploded in the eastern district of Qaboun on Saturday and initial reports said several people were killed while dozens were injured.
Activists on Saturday in Damascus said bodies were still being recovered from wreckage caused by the explosion. The UK-based Syrian Observatory for Human Rights put the death toll at five people.
Also in Damascus, clashes between rebel fighters and forces loyal to President Assad took place on the edge of the southern neighbourhood of Hajar al-Aswad.
Opposition fighters are also reportedly engaged in fighting with the regime’s forces in Qasyon, while the army continues to target armed groups in Daraya in the outskirts of Damascus, leaving dozens killed and injured.
The latest reports of violence came as the al-Nusra Front (Jubhat al-Nusra), a group of fighters in Syria, declared what it called a "no-fly-zone" over Aleppo, stating that the Syrian army was using commercial flights to transport military equipment and troops.
In a video sent to Al Jazeera, the group warned any civilians against boarding commercial flights to avoid being used as human shields.
They also confirmed laying siege on the al-Nairab airfield, adding that any plane over the skies of Aleppo will be targeted.
Al-Nusra told Al Jazeera they would use anti-aircraft guns of 23mm and 57mm calibre to down planes.
The US, earlier this month, has put al-Nusra on its list of "terrorist organisations".