All six members of Yukos' management committee have now left Russia, including chief executive officer Steven Theede and chief financial officer Bruce Misamore, both US citizens who have left for London. Yukos is now adrift as it faces ruin under a $US25 billion ($NZ35.59 billion) back tax demand.

Yukos' Russian operational managers, Alexander Temerko, Mikhail Trushin and production chief Yuri Beilin have also left the country. Refining and marketing head Pyotr Zolotarev has resigned, a Russian source told Reuters.

"All top managers have left the country because of the atmosphere of fear and terror aimed at paralysing the company," the source was reported as saying. "The company has been decapitated."

Middle management has also been harassed and been subjected to repeated house searches, according to the report.

The flight of Yukos’ executives could allow the Russian government to become the new owner of the oil concern, industry analysts told the New York Times.

“This could give the state legal grounds to install outside management," said James Fenkner, head of research at Troika Dialog, a Moscow brokerage firm.

The crippling tax demand is seen by many as the price the company has paid for former CEO Mikhail Khodorkovsky having challenged President Vladimir Putin.

Khodorkovsky and associate Platon Lebedev are on trial for fraud and tax evasion.

Khodorkovsky's other partners went into exile last year, following other business magnates like Vladimir Gusinsky and Boris Berezovsky who left Russia after surrendering their business empires.

To recover Yukos' tax debt, the state will auction its main Siberian unit, Yuganskneftegaz, on December 19 at a starting price of $US8.65 billion, half its estimated minimum value.

Investors fear the state will sell more assets, including Yukos' two other oil units and five refineries, leaving zero value to minority shareholders who own 25 per cent of Yukos.

Analysts expect Yugansk to be sold to gas monopoly Gazprom or pro-Kremlin oil firm Surgutneftegaz.

Speculation has mounted that Gazprom is trying to persuade its biggest Western clients, German Eon and Italy's ENI, into joining the auction.

Eon said it may be interested in purchasing Yukos' gas units, but has no plans to bid in the upcoming Yugansk auction.

“If as assets from Yukos were to come on the market, then we would look at them,” Eon chief Wulf Bernotat told the Financial Times Deutschland.

“[But] we are not interested in the upcoming auction for Yuganskneftegaz. It is almost exclusively about oil. Everything that is connected with Yukos is subject to considerable legal risks, so we would have to very carefully check whether we wanted to become involved."

It now seems likely India’s state-owned Oil & Natural Gas Corp (ONGC) will bid for the assets of Yukos, according to the country’s Petroleum Secretary SC Tripathi.

“ONGC has discussed bidding for Yukos assets at a very preliminary level. It is a good idea and we have asked them to go ahead,” The Indian Express reported him as saying.

Tripathi said ONGC would probably look at partnering with foreign firms like Gazprom of Russia due to the huge cash involved in the deal.

So far, oil production at Yukos has not dropped off, despite the company's wrangle with the Kremlin. Yukos produces 1.7 million barrels a day, or about 2 percent of the world's oil supply.