Rosneft is seeking to borrow up to $30 billion from China in exchange for possibly doubling oil supplies, making Beijing the largest consumer of Russian oil.

Four industry sources familiar with the situation told Reuters that Rosneft was in talks with Chinese State firm CNPC about the borrowing, which would echo a $25 billion deal the two companies clinched last decade.

Rosneft said it was not currently in talks about obtaining a loan from China but declined to comment when asked whether it may enter in negotiations at a later date.

In the previous deal, Rosneft and Russian pipeline monopoly Transneft borrowed money to help Rosneft acquire the assets of nationalized oil producer YUKOS while agreeing to build a pipeline to supply China with 300,000 barrels per day for 15 years.

This time, Rosneft wants to borrow money as it is close to completing a $55 billion acquisition of rival TNK-BP to become the world's largest listed oil producer.

Russia's leading oil company, controlled by the Kremlin, is considering ultimately doubling supplies to China, sources said. "It can be a combination of delivery options. The strategic line is to increase supplies to China," one source familiar with the situation said.

"The reason why China is willing to lend is simple. They sit on over 3 trillion of dollars in reserves and are looking to diversify their investments," he added, referring to China's foreign exchange reserves of $3.3 trillion.