China National Petroleum Corp (CNPC) and China Petrochemical Corp (Sinopec), the country's two leading oil and chemical companies, have no major oil refineries or chemical projects in the regions most seriously affected by the Sichuan earthquake last Monday.

A major refined oil pipeline in western China that had to shut down after Monday's massive earthquake is back in service, CNPC said.

The Lanzhou-Chengdu-Chongqing pipeline was able to carry 600 cu m of refined oil per hour after a 22-hour suspension following the quake, said the company.

The 1,250 km pipeline starts in the oil-rich northwest and ends at Chongqing, going by way of Gansu, Shaanxi and Sichuan.

China's largest oil refiner, Sinopec said that most natural gas wells in its southwestern branch were closed after the quake, but the influence was slight on wells and oil refining plants in northeast Sichuan. The company's largest Puguang natural gas field in northeast Sichuan did not sustain major damage.

In order to assist the rescue work, CNPC and Sinopec had increased fuel supplies to the earthquake-hit regions.

CNPC announced an emergency move to allocate 100,000 tons of refined oil to ensure supplies.

The company ordered some refineries to increase their production and one, its Lanzhou refinery, had increased production by 10 percent.

Sinopec also announced to supply 20,000 tons of diesel and 10,000 tons of gasoline to the regions.