Russian oil firm Yukos has lost an appeal against the sale of its Yuganskneftegas production arm, Russian media have reported.
Yukos says the authorities are seeking its destruction
Yuganskneftegas, which accounts for three-fifths of Yukos's output, was put up for auction after being seized to pay a tax bill totalling up to $25bn.
Yukos argued that tax officials could raise the money in other ways than selling its production unit.
The auction now seems likely to go ahead as planned on 19 December.
Tax officials have priced Yugansk at $8.65bn - hugely undervaluing it, according to the company's board.
Prosecutors searched Yugansk's offices on Friday.
Russian gas firm Gazprom is seen as the leading contender to buy Yugansk. The Kremlin is thought to want to tighten government control over Yukos, and to favour a sale to state-controlled Gazprom.
India's oil minister has said that Russia's President Vladimir Putin had "welcomed bids by Indian firms, either on their own or in collaboration with Russian firms". President Putin is on a three-day visit to India.
Earlier in November, Yukos accused the Russian government in a statement of seeking to bring about the firm's "total destruction".
The entire management board has left Russia in the wake of a summons from prosecutors wanting to interview Yukos's finance chief.
The sale of Yugansk comes after more than a year of tension between the Kremlin and the company, which began with the arrest of its chief executive Mikhail Khordokovsky on a Siberian airstrip in November 2003.
Mr Khordokovsky is on trial separately for tax evasion and fraud. He stood down as chief executive shortly after his arrest.