Under the agreement CNPC will purchase around 5.13 billion barrels of Russian oil between 2005 and 2030.

The deal is a major step toward the construction of a $US2.5 billion, 2,400-kilometre pipeline from the east Siberian city of Angarsk to Daqing in northern China.

The Russian state-owned pipeline monopoly, Transneft, and CNPC will jointly oversee the construction of the pipeline, which is expected to be finished in 2005.

The pipeline will carry 20 million tons of crude annually through 2010 and 30 million tons per year after that, with Yukos meeting about 10% of Chinese oil needs.

The contract was reached a day after President Vladimir Putin and visiting Chinese President Hu Jintao signed a declaration to increase cooperation between their two countries in a number of areas, including energy. The declaration named the Angarsk-Daqing pipeline as a cornerstone for future joint energy projects.

It was unclear on Wednesday whether Yukos would be the sole supplier of crude to China. By law, oil companies must be allowed equal access to pipelines.

Yukos and CNPC on Wednesday also signed a $1.1 billion agreement to ship 6 million tons of crude to China by rail over the next three years. The agreement effectively doubles the volume Yukos currently supplies to CNPC.

Meanwhile, the CNPC president met with Gazprom chief executive Alexei Miller on Wednesday to discuss joint projects including the construction of a Russia-China-Korea natural gas pipeline from the east Siberian Kovykta field. The field, controlled by BP and Tyumen Oil Co., is estimated to have 1.9 trillion cubic metres of natural gas.

The Russian firm is also set to acquire its rival Sibneft to create the country's largest and the world's number four private oil firm. The complex deal has been valued at up to $12 billion with the combined firm producing 2.3 million barrels per day of crude oil, putting it on par with OPEC member Kuwait and giving it 29% of crude oil production in Russia.