Russian President Vladimir Putin said his country will give priority to China over Japan for oil supplies from a pipeline project cutting through the country.

Japan's Kyodo news agency was quoted by Xinhuanet as saying that Putin made the remarks during a news conference after the three-day G8 summit in Gleneagles, Scotland.

Both Japan and China have tried to woo Russia to favour it in planning the pipeline's route that links eastern Siberia with the Russian Far East.

Beijing, which had initially inked the deal for a pipeline from the Siberian oil fields to Daqing, later offered Moscow more than $13 billion.

In April, Moscow issued an order for the pipeline to be built from Taishet to the halfway point at Skovorodino near the Russian-China border, triggering worries in Tokyo that oil supplies would go to China first.

Putin made it plain this time that the construction of the Pacific-bound pipeline will be contingent on development of a new oil field in eastern Siberia, where the amount of oil deposits remains unconfirmed.

Japan has told Russia it may not offer financing for the pipeline project if the prospect of Russian oil reaching the Sea of Japan coast diminishes.

The pipeline is expected to funnel 80 million tonnes of oil a year.