Russia’s state-owned petroleum company Rosneft acquired Yukos’ main production unit – Yuganskneftegas – last week ago when it was auctioned by the Kremlin to pay outstanding tax bills.

Rosneft is about to be merged with state gas monopoly Gazprom, but Russia's energy minister Viktor Khristenko said Yuganskneftegas, which accounts for 11% of Russian oil output, would be spun off from Rosneft and “transferred to a separate company 100% owned by the state,” according to a Financial Times report.

"The main incentive behind this move is to protect both Gazprom and Rosneft from legal risks," an oil analyst at the Aton brokerage Steven Dashevsky told the BBC.

Khristenko said the offer of 20% to CNPC was part of earlier agreement between Russia and China which also included a possible purchase of CNPC assets by Russian companies. One analyst said this was part of the Kremlin's effort to forge a new strategic alliance with China in face of its cooling relationship with the US, according to the Financial Times.

Another analyst told the Canadian Broadcasting Corporation that bringing in a foreign partner might also be designed to help Russia legitimise the nationalisation of Yuganskneftegaz in the eyes of the international community.

China has a huge appetite for oil, but it remains to be seen whether it would be willing to buy into Yukos assets while they are still subject to a US court injunction. CNPC has not commented on the reports.

It was widely believed that Gazprom was supposed to end up with Yuganskneftegas. But the state gas monopoly was forced to pull out from the auction following the US court injunction prohibiting it to participate in the sale of Yukos's assets.

The move to set up a new company appeared to signal the Putin Government aims to shield Gazprom from anticipated lawsuits filed by Yukos and its shareholders over the sale of Yuganskneftegas, according to a Canadian Broadcasting Corporation report.