Russian state-controlled gas firm Gazprom has filed an appeal in U.S. district court seeking to overturn a judge's order blocking the auction of Yukos' main oil producing subsidiary.
Yukos, which has financial holdings in the United States, filed for bankruptcy in Texas this week and won a 10-day restraining order against the sale from a court in Houston.
Russia said earlier it would proceed with the auction Sunday disregarding the U.S. court' s order. Russian officials say the sale of Yuganskneftgaz is in accord with Russian law, and U.S. courts have no jurisdiction.
However, Gazprom is facing trouble in securing financing from U.S. and European banks which reportedly put on hold a $10 billion loan awaiting the U.S. court's final decision.
Russian authorities ordered the sale to help cover Yukos' tax bill of more than $27 billion.