Karina Moskalenko said the court decision will provide additional time to thoroughly study the case files.
Both men are serving eight-year jail terms in Siberia for fraud and tax evasion.
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 repeatedly 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.
