Syrian activists, including Rami Abdul-Rahman who heads the Britain-based Syrian Observatory for Human Rights, say it is not clear how much of the fields are controlled by the rebels. Still activists and state media state say most of Syria's fields are no longer under direct government control. In November, rebels made one of the biggest gains when they briefly captured the large al-Omar field in Deir el-Zour only to lose it to government troops days later. They still control many other fields, the Observatory says.So far, the rebels have largely been unable to benefit from the oil fields, particularly since the country's two refineries in the central city of Homs and the coastal city of Banias are in the hands of Assad's troops. Regime warplanes' control of the air makes it difficult for rebels to exploit the fields, as do the divisions among rival rebel factions. "A number of challenges exist. In view of their lack of cohesion, the various strands of the armed opposition are unlikely to be able to mobilize in a unitary fashion to produce and export," said Anthony Skinner, Middle East-North Africa chief at the British risk analysis firm Maplecroft. "Rebels also clearly lack the engineers and qualified workers to ensure uninterrupted production from the oil fields," Skinner added. "Even if they were to do so, the regime would seek to bomb identifiable vehicle tankers to prevent the armed opposition from earning revenue to buy heavy weaponry." But looting is rife. A Syrian activist in the province of Hassakeh said some people in the area are using primitive ways to refine oil. Thieves put crude into tankers, then set fires around it until the fuel begins to turn to vapor that passes through a metal hose. The hose is cooled with water to condense the vapor, and gasoline, kerosene or diesel is produced, said the activist, who spoke on condition of anonymity for fear of government reprisals.