The Khamovnichesky court began hearings on Tuesday on new charges against Khodorkovsky of embezzling about $50 billion from his former company Yukos's affiliate, which could see his jail term extended by 21 years.
Rosneft has filed a damages lawsuit against the businessman and his business partner, Platon Lebedev, for an undisclosed sum. Rosneft bought up the bulk of Yukos's assets when the oil company was broken up and sold off to meet debts.
Khodorkovsky said Rosneft and the federal property agency's presence in the list of complainants was illegal, as they had not owned stakes in Eastern Oil Company (VNK), Yukos's affiliate whose shares the businessmen are accused of misappropriating in 1998-2000.
Defense lawyers acting for Khodorkovsky and Lebedev, who are serving eight-year sentences on fraud and tax evasion charges, have called their clients political prisoners, and the new charges "disgraceful" and unsubstantiated.
Khodorkovsky again accused prosecutors on Tuesday of refusing to carry out a fair investigation into the new charges.
"Personally, I am fed up with all of this," he said in a statement.
The court earlier rejected the defense's request to drop the new charges and return the case for further investigation, as well as to change the judge and state prosecutors over alleged bias.
