Jailed Russian oil tycoon Mikhail Khodorkovsky was sentenced to six more years in prison Thursday following a trial seen as payback for his defiance of Vladimir Putin's power.

Judge Viktor Danilkin sentenced Khodorkovsky to 14 years after convicting him of stealing oil from his own company and laundering the proceeds, but the judge said the new sentence is counted from his 2003 arrest and includes his previous term in jail. Khodorkovsky is in the final year of an eight-year prison sentence.

Putin, now prime minister, is seen as the driving force behind the trial of Khodorkovsky, who challenged him during his presidency. Eyeing a return to the presidency in 2012, Putin appears unwilling to risk the possibility that a freed Khodorkovsky could help lead his political foes.

Following his 20-month second trial, the judge convicted Khodorkovsky and his business partner Platon Lebedev on charges of stealing around $27 billion worth of the oil that his Yukos company produced from 1998 to 2003 and laundering the proceeds. Defense lawyers said much of the judge's verdict was copied from the indictment and the prosecutors' final arguments.

The judge also sentenced Lebedev to fourteen years.

The defense called the charges ridiculous, saying they reflected the lack of understanding of the oil business, including the payment of transit fees and export duties.

The outcome of the second trial exposes how little has changed under President Dmitry Medvedev despite his promises to strengthen the rule of law and make courts an independent branch of government. The Russian Foreign Ministry has dismissed Western criticism of the trial as unacceptable pressure.