Mikhail Khodorkovsky, Russia's richest man and former CEO of oil giant Yukos, pleaded innocent to all charges against him during a court hearings session Thursday, Interfax news agency reported.

"I have understood the indictment presented, and I plead not guilty to all counts," Khodorkovsky told the court.

Platon Lebedev, a close associate and another key shareholder of Yukos, also pleaded not guilty to all charges against him.

Khodorkovsky said he and Lebedev would address the charges against them in further detail during Friday's court session.

Lebedev, CEO of Group Menatop, was arrested last July. His arrest and the following arrest of Khodorkovsky last October were seen by some analysts as the start of the year-long judicial campaign to stifle the financial and political clout of Khodorkovsky, who had reportedly sponsored political opponents against President Vladimir Putin.

But the Kremlin has repeatedly denied any political motive behind the Yukos case, saying it is part of the country's anti-corruption campaign to crack down on economic crimes. Last month, Putin said the government was not interested in seeing the oil giant driven into bankruptcy.

Both Lebedev and Khodorkovsky face seven charges including fraud, embezzlement and tax evasion in connection with the 1994 privatization of a big, state-owned fertilizer plant.

The government estimates that their actions cost the state more than 1 billion US dollars.

The two tycoons could be sentenced 10 years in prison if convicted.

A 44-percent stake in Yukos owned by Group Menatop has been frozen by prosecutors.

The Moscow's Meschchansky district court resumed combined hearings on the criminal case against Lebedev and Khodorkovsky on Monday.

Yukos, founded by Khodorkovsky, faces a 3.4-billion-dollar back taxes bill for the year 2000.

Court bailiffs last week began to seize bank accounts of Yukos subsidiaries throughout Russia as payment after a five-day deadline to pay the bill expired.

The company has received another claim of 3.3 billion dollars in back taxes by the tax authorities for the year 2001 and could face further sanctions for 2002 and 2003.