Russia's one-time richest man is currently serving an eight-year sentence for fraud and tax evasion.
Semyon Rozenberg, a lawyer for Khodorkovsky, said that the defense had appealed the court ruling that extended the former oligarch's custody as part of a new investigation into money laundering.
The Chita court on October 8 extended Khodorkovsky's custody until February 9, 2009, as investigators look into accusations of stealing oil and laundering money totaling $28.3 billion between 1998 and 2004.
Khodorkovsky has consistently maintained his innocence, saying he has been punished for supporting the country's pro-Western opposition, and that the subsequent liquidation of Yukos was engineered by corrupt government officials aiming to seize lucrative oil assets.
