Yukos, accusing Russian authorities of illegal action against it, said it had asked US legal authorities to block the sale of Yuganskeneftegaz scheduled for 19 December, arguing this would "cause it immediate and irreparable harm".

The company said it had asked the court for an emergency hearing and a temporary restraining order.

It wanted a preliminary injunction to halt the sale and to compel the Russian authorities to arbitrate the company's claims of billions of dollars in damages.

Yukos, which has been suffering severe problems for more than a year over a tax dispute, said that the subsidiary accounted for 60% of its oil production.

It said the Yukos Oil Company's bank accounts and other assets had been frozen by the Russian authorities "as part of an unprecedented campaign of illegal, discriminatory and disproportionate tax claims".

These had escalated into "raids and confiscations, culminating in intimidation and arrests".

The existing management continued to run the business and manage its assets as "debtor-in-possession".