Reuters reports that Sibir has won a court injunction against Sibneft, accusing Sibneft of effectively stealing the Priobskoye oilfield in Western Siberia that the companies own and operate through a joint venture.

Sibir claims Sibneft illegally diluted its interest from 50% to under 1% by secretly selling shares in the joint venture, called Sibneft-Yugra, to companies affiliated with Sibneft.

But Sibneft denies any wrongdoing, saying it acted within the broad scope of the JV operating agreement.

Forbes magazine describes Abramovich – who bought current Premier League titleholders Chelsea for US$100 million in 2003 - as Russia's richest man, with a US$14.7 billion fortune.

Sibir is controlled by Shalva Chigirinsky, a Russian construction and oil magnate, whom Forbes in May said was worth US$470 million.