MOSCOW, Sept. 17 -- Russian energy giant Gazprom plans to sign a 30-year gas supply contract with China via the western route, the company's CEO Alexei Miller said Wednesday.

"Gazprom plans to sign a contract to supply China with 30 billion cubic meters of natural gas via western route over thirty years," Miller told President Vladimir Putin during their meeting here.

The China-Russia West Route natural gas pipeline project connects gas deposits in Western Siberia and the northwestern part of China via Russia's Altai region. Gazprom is to sign the 30-year contract with China National Petroleum Corporation (CNPC) in November.

Miller also said Gazprom might consider more than doubling the volume of supply.

"During the talks about new contracts on the western route, a possibility of supplying 60 billion to 100 billion cubic meters is being considered," Interfax news agency quoted him as saying.

According to Miller, Gazprom plans to use the existing pipeline infrastructure to implement the western project, which would need less investment than construction of the eastern one.

China and Russia signed the China and Russia Purchase and Sales Contract on East Route Gas Project and a memorandum in May, and the 30-year contract will see the east route pipeline start to provide China with 38 billion cubic meters of natural gas annually from 2018.

The Russian part of the joint venture pipeline, officially dubbed "Power of Siberia", will be built by Gazprom with a total investment of 55 billion U.S. dollars. Construction of the China- Russia East Route natural gas pipeline started in this eastern Siberian city of Yakutsk on Sept. 1.