BEIRUT - Syrian government forces seized around half of a key opposition-held neighborhood in Aleppo on Thursday in a new advance against rebels, the Syrian Observatory for Human Rights monitoring group said.The British-based Observatory said fighting had been raging in the residential Bustan al-Basha quarter near the city center, one of the front lines in Aleppo which has been dived for years between government and opposition areas of control.The Syrian military also said in a statement that its forces had advanced in Bustan al-Basha.Government forces have with the use of heavy aerial bombardment encircled Aleppo's rebel-held eastern sector in recent weeks and are seeking to completely recapture the city.