MOSCOW (CNN) - A Russian court found oil magnate Mikhail Khodorkovsky and his business partner Platon Lebedev guilty of tax evasion and other serious crimes on Tuesday and sentenced each to nine years in prison, Russia's Interfax news agency reported.

The court also ruled that the men pay another 17 billion rubles in back taxes, roughly $600 million.

Khodorkovsky, 41, has been held in prison since his arrest in 2003. Yukos, which has since been crushed under the weight of a $27.5 billion back-tax bill, has been the object of a lengthy campaign by prosecutors and tax authorities.

Tuesday's decision completes the lengthy process that began April 27 as the judges began summing up their verdicts in the 11-month hearing.

The prosecution sought the maximum 10-year prison term for Khodorkovsky, while his defense team wanted him fully acquitted.

Khodorkovsky and Lebedev -- a Yukos minority shareholder -- faced almost identical charges.

The two had been listening to their fate from the metal cage in the courtroom where they had watched the trial since it started last June.

The Russian Prosecutor General's Office said it was satisfied with the court's ruling.

"We find the verdict fair and objective," spokeswoman Natalia Vishnyakova said, according to Interfax. "It matches the actual circumstances of the case and the gravity of the crimes committed by the defendants."

But a Yukos statement called it a "gross travesty of justice."

"Yukos employees view the verdict as a gross travesty of justice produced by a judicial system that has not only been content to be maneuvered to destroy Mikhail Khodorkovsky, but also apparently is intent on bringing down Yukos," the statement said, according to Interfax.

Company officials have said the crackdown was the Kremlin's punishment for Khodorkovsky's politics.

Khodorkovsky, who has criticized President Vladimir Putin, funded opposition political parties and expressed a desire to run for office some day. Putin has said the case is part of a crackdown on corruption, and he denies political motivation.

Khodorkovsky branded the trial a farce from its start. It has been widely seen as part of a Kremlin campaign to destroy him and take back the company he built in murky privatization deals of the 1990s.

The Kremlin, which suspects Khodorkovsky of having dangerous political ambitions, has denied any role in his downfall. But Putin's chief of staff Dmitry Medvedev has described the trial as "showcase" for other business leaders.

"I expressed my concerns about the case to President Putin because... it appeared to us -- at least people in my administration -- that it looked like he had been adjudged guilty prior to have a fair trial. In other words, he was put in prison and then was tried," President Bush said in a press conference Tuesday.

U.S. Secretary of State Condoleezza Rice said last month in Moscow that Washington was watching the trial closely for signs of what it showed about the rule of law in Putin's Russia.

For more on Khodorkovsky's embattled Russian oil company, click here.