The humanitarian pause, which was to run from 8:00 am to 4:00 pm (0500 GMT to 1300 GMT), has been extended "by three hours until 7:00 pm (1600 GMT)," senior military official Sergei Rudskoi said at a briefing at the defence ministry in Moscow.
He said this was done after "numerous requests" from representatives of international aid organisations.
The extra time "will allow representatives of the United Nations and the Syrian Red Crescent to carry out all their operations to ensure the evacuation of the sick and wounded, and also to allow peaceful civilians out of the city," the military spokesman said.
Moscow announced yesterday morning that Russian and Syrian air forces had stopped bombing Aleppo ahead of the pause in fighting and the halt held into a second day today.
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According to Moscow, once the pause begins six corridors out of the city will open for civilians with another two -- via the Castello Road in the north and Souk al-Hal in the city centre -- designated for rebels.
Rudskoi also said Russian and Syrian planes were keeping 10 kilometres from Aleppo after Moscow pledged yesterday to stop bombing the city ahead of the truce.