BEIRUT, March 7 (Reuters) - Syrian rebels in eastern Ghouta will defend the territory and there are no negotiations over a withdrawal that has been proposed by Russia, the military spokesman for one of the main eastern Ghouta rebel groups said on Wednesday. "There are no negotiations about this subject. The factions of Ghouta and their fighters and its people are holding onto their land and will defend it," Hamza Birqdar told Reuters in a text message. Russia, President Bashar al-Assad's most powerful ally, has offered to give rebel fighters safe passage out of eastern Ghouta, near the capital, Damascus, with their families and personal weapons. Meanwhile, The Russian military said late on Tuesday that it had helped evacuate 13 civilians from Syria's eastern Ghouta by putting them on returning trucks that had brought aid to the rebel-held area near Damascus. Aid trucks reached Syria's eastern Ghouta region on Monday for the first time since the start of one of the war's deadliest assaults, but the government stripped some medical supplies from the convoy and pressed on with its air and ground assault.