A Moscow court threw out a series of appeals yesterday from the embattled Yukos oil company, scuppering its efforts to suspend a government demand for $3.4 billion (€2.8 billion) in unpaid taxes that Russia's biggest oil firm says could force it into bankruptcy.

Judges rejected six appeals from Yukos, including one to have them removed from the case for alleged bias, a day after President Putin said the government would do everything it could to save the firm from insolvency.

Shortly after the Mr Putin's comments, Yukos criticised former top executives - many of whom are accused of major financial crimes - for underpaying corporate taxes for 2000-2003, in a "mea culpa" open letter that offered to hand assets to the government or state-run firms in return for the chance to raise cash and avoid bankruptcy.

The offer is seen as part of delicate and shadowy talks between officials and Yukos management over the future of the firm and its founder, Mr Mikhail Khodorkovsky, who is on trial for alleged tax evasion and massive fraud.

He says he is being persecuted for criticising former KGB agent Mr Putin and funding opposition groups; the Kremlin insists he is simply being tried alongside allies in Yukos for breaking the law and robbing Moscow's coffers of billions of dollars.

Yukos' share price has been battered by a year-long legal onslaught over financial issues which, according to many analysts, apply to scores of Russian companies that were sold off in the mid-1990s at knockdown prices in rigged auctions.

The tax ministry claims Yukos used onshore tax havens to minimise its tax liability, but the company insists that any tax schemes it used were legal, and that many of the alleged liabilities apply to unrelated companies.

Analysts are still in the dark over what the end game will be for Yukos and Mr Khodorkovsky.