Bankrupt Russian oil company Yukos sold its last large assets for $3.89 billion at auction on Friday.

Prana, thought to represent the interests of a larger company, bought the Yukos properties after a hard-fought bidding war against Russian state oil company Rosneft. The winning bid came in at more than four times the properties' starting price.

This was the 13th auction since Yukos declared bankruptcy last August, after founder Mikhail Khodorkovsky was sentenced to eight years in prison for $30 billion in tax fraud.

Rosneft has been by far the largest beneficiary of the auctions, winning four of them and, last week, becoming the country's top oil producer after scooping up Tomskneft for $6.8 billion. But the unknown Prana beat the state oil champion on Friday, after three hours and more than 700 bids for Yukos' real estate.

"We bid up to the limit that we thought possible," a Rosneft spokesman told the agency.

The centrepiece of the lot was Yukos' 22 story former headquarters, located next to central Moscow's Paveletsky Station.

Three final auctions, expected to fetch little more than 400 million dollars, are expected to take place by June 7. Most of the assets to go on the block then are investment vehicles and oil services companies.