Medvedev's comments came only a week after Prime Minister Vladimir Putin compared Khodorkovsky, once Russia's richest man, to the U.S. disgraced financier Bernard Madoff who cheated investors out of an estimated $20 billion through a Ponzi fraud. Putin said Khodorkovsky deserves no leniency — a statement widely denounced as interfering in the trial.

"Neither the president nor any other state official has the right to comment on this particular case before the verdict is passed," Medvedev said in a live interview with Russia's state TV stations.

Khodorkovsky was convicted of underpaying taxes on the profits from his Yukos oil company and is serving an eight-year sentence. His case has been widely seen as punishment for daring to challenge the Kremlin's political and economic power during Putin's presidency, in part by funding opposition parties in parliament.

Khodorkovsky is now facing a second trial on charges of embezzling $25 billion worth of oil. A judge is to begin delivering the long-awaited verdict on that case Monday.

Medvedev, who has promised to establish independent courts and strengthen the rule of law in Russia, insisted that he saw no evidence to support claims that prosecutors were selective in applying the law and punishing the tycoon for common business practices.