China won its first Russian oil industry foothold with the purchase by giant Sinopec of a major subsidiary to the Russian-British oil group TNK-BP.

The deal between TNK-BP and Sinopec (China Petroleum and Chemical Corp), the second biggest Chinese oil company, is the latest step by the country to satisfy a booming economy with sufficient energy supplies.

TNK-BP, which is Russia's second largest producer after state-owned Lukoil and Rosneft, said in a statement it had "reached agreement with Sinopec for the sale of its Udmurtneft assets."

But Sinopec will have to share its acquisition with state-owned oil company Rosneft, which said Tuesday it would exercise an option to acquire a controlling 51 percent of shares in Udmurtneft.

Udmurtneft, which controls 26 fields in the province of Udmurtiya, just west of the Ural Mountains, produces six million tons of oil a year, according to data on TNK-BP's website.

No value to the deal was given, but earlier the oil company's chief executive Robert Dudley had estimated the sale could bring in around three billion dollars.

"This is a positive development. It brings another major international investor working with strong Russian alliances into the country's oil and gas sector. It reinforces Russia's pivotal role in global energy markets," Dudley was quoted as saying in the statement on Tuesday.

"For TNK-BP it will allow us to concentrate more resources on our core exploration and production regions in Russia," he continued.

TNK-BP is 50 percent owned by British oil major BP and 50 percent by a group of Russian investors. The company produced 72 million tons of oil in 2004 and currently pumps around 1.5 million barrels per day, its website said.

China, where oil consumption is expected to grow by six percent this year, has already gained access to oil in Kazakhstan, with the opening in May of a new pipeline.

In 2002 Chinese oil company CNPC withdrew from competing in the purchase of privatised Russian group Slavneft.

More recent rapprochment between Moscow and Beijing has improved the climate and President Vladimir Putin has repeatedly said that Chinese companies could enter the Russian market.