ConocoPhillips is considering buying a stake in Lithuania's Mazeikiu Nafta refinery, which is controlled by Russia's embattled Yukos company, the chairman of the U.S. oil and gas producer said Wednesday.

"It is possible that over some time we could acquire ownership interests in Mazeikiu Nafta," ConocoPhillips Chairman and Chief Executive James J. Mulva told reporters in Vilnius.

Yukos holds a 53.7 percent stake in Mazeikiu Nafta, Lithuania's only refinery, while the Lithuanian government holds a 40.6 percent stake. The refinery, which includes a pipeline and offshore oil terminal, accounts for around 10 percent of Lithuania's gross domestic product.

Russian oil giant Lukoil, in which Houston-based ConocoPhillips has a stake, has also expressed interest in buying stakes in the refinery from Yukos.

Mulva, who was speaking to reporters after a meeting with Lithuanian Prime Minister Algirdas Brazauskas, did not rule out that U.S. and Russian companies could be partners in running the Lithuanian refining complex. 
 
ConocoPhillips' stake in Lukoil stands at 11.3 percent. The company has said it intends to exercise its option to raise that to 20 percent this year.

The Russian Justice Ministry asked that Yukos' share in Mazeikiu Nafta be frozen, the Interfax news agency reported Wednesday.

Analysts noted that it would be unlikely for Conoco, Lukoil or any other potential buyer to continue negotiations with Yukos over shares that might be subject to a freeze.

Yukos saw its main oil producing subsidiary auctioned by the government last year against some $28 billion in back tax claims. But a court-ordered freeze on its assets in Russia since last year had not been applied to its controlling stake in Mazeikiu Nafta.

Interfax said the ministry asked the Netherlands and Lithuania to identify assets on their territory belonging to Yukos as it presses ahead with the collection of the tax debts.

Observers see the cases against Yukos as a Kremlin-orchestrated campaign to punish the company's founder Mikhail Khodorkovsky for his political ambitions, while the government insists they are a just enforcement of law.