Lawyers of jailed Russian tycoon Mikhail Khodorkovsky filed an appeal today against his conviction on tax evasion and fraud charges.
Khodorkovsky was sentenced to nine years in prison ten days ago in a case widely seen as a Kremlin-inspired attack on a politically ambitious opponent.
The case, and the long sentence imposed, have stoked concerns among investors about the rule of law in Russia, which effectively nationalised the main unit of the magnate's Yukos oil firm during his detention.
"The defence thinks the verdict is illegal and unfounded, and asks that it be cancelled and the trial halted," lawyer Genrikh Padva told Interfax news agency.
A spokeswoman confirmed the appeal had been filed.
Khodorkovsky, once Russia's richest man and most prominent "oligarch", was found guilty on six of seven charges of fraud and tax evasion after an 11-month trial.
Prosecutors have pledged to bring more charges against him and business associate Platon Lebedev, who was tried with Khodorkovsky and also sentenced to nine years in jail. Lebedev has already appealed.
Yukos, once Russia's most efficient oil company, was crushed by claims of $27.5 billion in back tax, and main unit Yuganskneftegaz was auctioned off last year.
State oil firm Rosneft later bought the unit from a murky financial vehicle that won the auction.