Syrian civil defence volunteers, known as the White Helmets, rescue a boy from the rubble following a reported barrel bomb attack on the Bab al-Nairab neighbourhood of Aleppo. Pic/AFP

Geneva: Syrian rebels in besieged east Aleppo have agreed to a U.N. plan for aid delivery and medical evacuations, but the United Nations awaits a green light from Russia and the Syrian government, humanitarian adviser Jan Egeland said on Thursday.