Boris Gruzd said a representative of the Russian General Prosecutor's Office presented a report to the Chita court saying Khodorkovsky could evade justice if he were to be released from custody.
A court earlier extended a probe in the Siberian city of Chita into a second set of charges against Khodorkovsky and his ex-business partner Platon Lebedev, who are serving an eight-year sentence on fraud and tax evasion charges, until August 2.
The latest charges against Khodorkovsky and Lebedev, both convicted in 2005, include stealing government shares, illegal oil trading, and laundering $25 billion earned from oil sales in 1998-2004.
Both have maintained their innocence of all the charges. Khodorkovsky said his imprisonment was a direct result of his support for Russia's tiny pro-Western opposition.
Yukos, once Russia's largest independent oil producer, collapsed after claims of tax evasion in 2004 which led to the company being broken up and sold off to meet creditor claims. The bulk of its assets were bought through liquidation auctions by government-controlled oil company Rosneft. The company was officially dissolved in 2007.
