Imprisoned former Yukos CEO Mikhail Khodorkovsky pleaded not guilty Tuesday to new embezzlement and laundering charges that are widely seen as politically motivated.

He and imprisoned business partner Platon Lebedev are accused of embezzling more than $25 billion worth of oil from subsidiaries of his Yukos oil company and laundering most of the proceeds.

"No, I do not admit my guilt," Khodorkovsky said calmly, standing in a steel-and-glass cage. "If I stole the oil ... and profits while the state got 40 billion rubles in taxes, what were the taxes paid for?" he added.

Lebedev, who also pleaded not guilty, called the charges "schizophrenic" and "blatantly falsified."

The defendants, who face up to 22 years in prison if convicted, describe the new charges as nonsense, saying they amount to an accusation that Khodorkovsky stole all the oil produced by Yukos from 1998 through 2003.

"The claim that 350,000 tons of liquid [oil] have been stolen or hidden makes no sense," Khodorkovsky said. "It's no bucket of paint stolen from a store."

Khodorkovsky, once the country's richest man, has been imprisoned since his arrest in 2003. In 2005, he was sentenced to eight years in prison on fraud and tax evasion charges. The accusations were seen as part of a Kremlin-driven campaign to punish him for challenging then-President Vladimir Putin and to increase state control over oil revenues.

The pair's supporters claim that the second trial is just a new phase of a reprisal campaign driven by political calculations, commercial interests and personal motives.

"The main problem of state prosecutors and the small-time corrupt vermin who profited on dismantling Yukos and who tried to stage this process is the need to cover their petty, greedy interests with lofty political goals," Khodorkovsky said.

The trial is being watched for signs of more judicial independence under Putin's successor, President Dmitry Medvedev, a former lawyer who has stressed the importance of the rule of law.

Khodorkovsky, however, remained skeptical about Medvedev's pledges.

"As president's words are one thing and [his] practical steps are the other, the new Yukos trial is very significant, almost symbolic," he said while prosecutors tried to shout him down.

Defense lawyers argue that Khodorkovsky and Lebedev are being tried a second time for the same actions.