MOSCOW, May 20 (RIA Novosti) - The Moscow City Court has postponed the hearing of an appeal by jailed Yukos founder Mikhail Khodorkovsky and his business partner Platon Lebedev against a second set of criminal charges against them.

The appeal was postponed due to "procedural irregularities."

The Moscow City Court is due to hear eight appeals by Khodorkosky and Lebedev following pretrial hearings at Moscow's Khamovnichesky District Court.

Among other matters, the court will also have to decide on whether the decision by the district court judge to continue with the second trial was in fact legal. The defense maintains that the second set of criminal charges against Khodorkovsky and Lebedev should be dropped as "groundless."

The two men, who are both currently serving eight-year sentences for fraud and tax evasion, were transferred from a Siberian prison to a Moscow detention center in February to stand trial on fresh embezzlement, oil theft and money laundering charges.

Their sentences could be extended by another 20 years if they are found guilty.

Lawyers acting for the businessmen, who have maintained their innocence throughout, have called their clients political prisoners, and say the new charges are "disgraceful" and unsubstantiated.