Russia's Justice Ministry has refrozen the assets of a key Yukos unit, despite a recent court order preventing such a move, according to reports.
Russian news agencies reported that bailiffs had seized assets belonging to Yuganskneftegaz in response to Yukos' failure to make required tax payments.
Yukos shares earlier surged after a court ruled on Friday that bailiffs could not seize control of the unit.
Yukos has warned it could go bust if the vital subsidiary is sold off.
Yukos was dealt another blow on Monday, Russian news agencies reported, when a court upheld the seizure of assets at a separate unit, Tomskneftegaz.
Yukos could not be reached for comment.
New woes
Yuganskneftegaz accounts for 60% of the oil firm's daily production of 1.7 million barrels.
Analysts fear that production may be halted if bailiffs attempt to break up the unit in order to pay the firm's outstanding £3.4bn tax bill for 2000.
The Justice Ministry's action, reportedly sanctioned by a court of arbitration in Moscow, took place after the end of trading on Monday.
During the earlier session, rouble-denominated Yukos shares climbed 16% to 128.65 roubles.
The market was buoyed by the previous court decision and comments from Russia's state railway that it expects to keep shipping Yukos's oil exports, even after its deadline to pay transport fees has expired.
Yukos lost a further appeal on Monday against the government's attempt to wrest control of a second unit.
The Moscow Arbitration Court ruled that the state was entitled to take control of assets belonging to the smaller subsidiary, Tomskneft.
The court deferred a similar decision on a third production unit, Samaraneftegaz, until next month.
'Great victory'
Uncertainty about its future has hit the value of Yukos' shares.
The stock has lost about two-thirds of its value since April, when the Kremlin started legal action to recover the unpaid taxes.
It appeared on Friday that Yukos had won a major victory when the Court ruled that the government had acted illegally by seizing control of the unit.
"This is perhaps the greatest victory for the company since the Justice Ministry's announcement a month ago that Yuganskneftegaz would be appraised for future sale," brokerage Troika Dialog said in a note to investors.
At the end of July, state bailiffs announced they intended to sell off Yuganskneftegaz and its assets were frozen.
Tax demand
Yukos has so far managed to pay $700m of its tax bill for the year 2000, and it said it plans to pay off the remainder soon.
However, some commentators have warned that if the government pushes through with 2001-2003 tax claims, Yukos' total tax bill could reach $10bn.
The firm's former boss Mikhail Khodorkovsky is currently in jail facing charges of fraud and tax evasion.
The battle between the Kremlin and Yukos is widely seen as stemming from Mr Khodorkovsky's decision to fund opposition political parties in Russia.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©