Since March PetroChina Company Limited, China's biggest oil producer, and Sinopec Limited, one of the major petroleum companies in China, have ceased supplying oil to private gas stations in Chongqing, forcing many of these stations into closing down. The trend is also being seen in other areas of China, according to a report from the China Securities Journal on Thursday.

An insider from the petrochemical industry revealed that Sinopec and PetroChina had interrupted oil supplies to private gas stations in some areas.

A sales representative who wished to remain anonymous, at an oil marketing company in Daxing district, Beijing, said that the amount of available oil in Beijing had indeed diminished, and that while the gas supply was relatively adequate, the supply of diesel oil faced a shortage.

Staff at a gas station said that even if the overall oil supply was sufficient, the oil giants would not be willing to supply oil to private gas stations, because oil prices charged to private gas stations are cheaper by 300 to 400 yuan ($46.20 to $61.60) per ton, which reduces the giants' profits.