BEIRUT - Mains water and electricity have returned to large parts of the Syrian city of Aleppo following a three-week cut after rebels stopped water supplies to pressure the government, a group monitoring the war said on Saturday.Al Qaeda's Nusra Front stopped supplies to government and insurgent-held areas of Aleppo by closing the city's pumping facility, forcing residents to drink untreated water from wells or resort to other emergency supplies, the Syrian Observatory for Human Rights monitoring group said.The water plant's manager belongs to the Nusra Front insurgent group and had urged the government in a letter to restore electricity supply it cut off in parts of the city in return for reactivating the pump, the Observatory said.Parties involved in the four-year Syrian conflict have frequently used access to water and electricity supplies as bargaining chips. In some areas enemy sides have struck deals to ensure essential supplies.The water plant manager has also called on the Syrian Arab Red Crescent (SARC) aid group to provide diesel for the water pump, the Observatory said. International aid groups in Syria usually partner with SARC at the government's request.A Twitter feed for SARC in Aleppo posted pictures on Friday showing its emergency water deliveries in the city but did not mention whether mains water had been restored. SARC officials were not immediately available for comment.Aleppo was Syria's most populated city and commercial hub before the conflict erupted in 2011. Destroyed to rubble in many areas, it has been carved up between government forces and various insurgent groups.The Britain-based Observatory, which tracks the conflict using sources on the ground, also reported that Syrian authorities released more than 350 prisoners on Thursday and Friday to mark the end of the Muslim holy month of Ramadan.Those released were mainly activists involved in protest movements at the beginning of the uprising and included prominent figures, the Observatory's founder Rami Abdulrahman said.