MOSCOW — Mikhail Khodorkovsky was convicted of theft and money laundering charges Monday, a verdict that will likely keep the jailed oil tycoon who was once Russia's richest man behind bars for several more years.The verdict came less than two weeks after Prime Minister Vladimir Putin said Khodorkovsky was a proven criminal who should sit in prison, a blunt statement reflecting his stance against the man who challenged his power — remarks denounced by critics as interference in the trial.Putin, who was president during Khodorkovsky's first trial, has shown no sign of softening his attitude toward the former oligarch. Putin has not ruled out a return to the presidency in 2012 and critics suspect him of wanting to keep Khodorkovsky incarcerated until after that election.It was clear from the opening pages of his verdict that the judge had found Khodorkovsky and his business partner Platon Lebedev guilty. Reading the full verdict and announcing the sentence was expected to take several days.Khodorkovsky, 47, is nearing the end of an eight-year sentence after being convicted of tax fraud in a case seen as punishment for challenging the Kremlin's economic and political power, in part by funding opposition parties in parliament.The conviction on charges of stealing around $27 billion worth of oil his Yukos company produced between 1998 and 2003 and laundering the proceeds could keep him behind bars until at least 2017.Prosecutors accused Khodorkovsky and Lebedev of stealing the oil from Yukos' own production units and then selling the oil abroad at higher prices. The defense called the charges ridiculous, arguing that prosecutors do not understand the oil business, including the payment of transit fees and export duties.Numerous witnesses, including current and former government officials, testified during the 20-month trial that the charges against Khodorkovsky and Lebedev were improbable if not absurd.One of Khodorkovsky's lawyers, Vadim Klyuvgant, on Monday dismissed the charges as fabricated and said that the guilty verdict was the result of official pressure."If the court were free and independent in issuing its verdict, it would have issued an acquittal," Klyuvgant told reporters. "What we heard here confirms that the court has faced pressure."Khodorkovsky's arrest in October 2003 and the subsequent state takeover of his Yukos oil company allowed the government to reassert control over the energy sector and tamed other wealthy businessmen, who have obediently followed Kremlin orders ever since. The Kremlin also consolidated its hold over political life. Soon after Khodorkovsky's arrest, parties that he had funded were shut out of parliament or sidelined.President Dmitry Medvedev, who despite his title remains Putin's junior partner, has promised to strengthen the rule of law as part of his mission to modernize Russia and attract more foreign investment. The outcome of the Khodorkovsky trial is seen as a test of whether Medvedev has any real intention — or real power — to deliver on his promises.Medvedev urged officials Friday to refrain from commenting on Khodorkovsky's case before the court rules — a statement seen by some as a tacit rebuke to Putin for his statement this month that the former tycoon deserves no leniency.