Russia and the Syrian government will open humanitarian corridors in Syria's embattled city of Aleppo and offer a way out for opposition fighters wanting to lay down their arms, Russia's defence minister Sergei Shoigu said.
The announcement came as Syrian dictator Bashar al-Assad offered a general amnesty for rebels who give up their weapons and surrender to authorities over the next three months.
Assad regime forces and allied troops have encircled the main rebel enclave in the city of Aleppo, urging fighters there to surrender.
Humanitarian groups have warned of a major catastrophe if the siege on the rebel-held parts of Aleppo continues.
Some 300,000 residents are trapped in the eastern part of the city that is controlled by rebels, according to the United Nations.
Humanitarian aid corridors in and out of Aleppo must be made safe, and no one should be forced to leave the city, UN aid chief Stephen O'Brien said in response to the Russian/Assad proposal.
"All parties are required and obliged under long-established and accepted international humanitarian law to allow safe, unimpeded, impartial and immediate humanitarian access for civilians to leave and come in," Mr O'Brien said.
Shoigu said in televised comments that President Vladimir Putin has ordered a "large-scale humanitarian operation" that will be launched outside Aleppo to help civilians as well as allow fighters who wanted to lay down the arms to surrender.
"Together with the Syrian government we will open three humanitarian corridors in order to help civilians who were kept hostage by the terrorists as well as the fighters who want to lay down their arms," he told a meeting in Moscow.
Moscow welcomes international aid organisations which operate in Syria to join the Russia-lead humanitarian operation, he added.
The fighters who want to surrender will be able leave the city via a corridor to the north, Shoigu also said.
Assad, meanwhile, issued a decree offering an amnesty to armed opposition fighters who surrender within three months and urging all detainees to be freed.
The decree, which was published by the state-run news agency SANA, said that those who might set free their captives will be exempted from punishment if they turn themselves in within a month.
Assad has issued amnesty offers several times in the past in the course of Syria's civil war, now in its sixth year. The offer is largely seen by opposition fighters as a publicity stunt and psychological warfare against the rebels.
More than a quarter of a million people have died and millions have been displaced since March 2011, when Syria's conflict erupted.