Syrian president Bashar Assad has offered an amnesty to rebels who lay down their arms and surrender to authorities over the next three months.
The offer was issued through a decree and urged that all detainees be freed.
It said those who free their captives will be exempt from punishment if they turn themselves in within a month, according to state-run news agency SANA.
The offer coincides with a government offensive which has completely encircled rebels in the eastern part of the city of Aleppo.
Russian defence minister Sergei Shoigu said Moscow and the Syrian government will open humanitarian corridors and offer a way out for so-called 'Islamic State' fighters wanting to lay down their arms.
Humanitarian groups have warned of a major catastrophe if the siege on the rebel-held parts of Aleppo continues.
Mr Shoigu said president Vladimir Putin has a "large-scale humanitarian operation" that will be launched outside Aleppo to "help civilians who were taken hostage by terrorists as well as fighters who wanted to lay down the arms".
He mentioned three humanitarian corridors as well as food and first aid points outside the city.