MOSCOW, Russia --Imprisoned oil tycoon Mikhail Khodorkovsky presented Russian prosecutors with a jar of crude oil Tuesday and demanded to know how anyone could siphon off 350 million tons of the stuff, as he has been accused of doing in a politically charged trial. The theatrical arguments were the most expansive he has been allowed to make since the legal assault on him began in 2003, and it included props like a laser pointer and a gallon of waste liquid from an oil well, which he encouraged prosecutors to smell. Once Russia's richest man, Khodorkovsky is accused of embezzling more than $25 billion worth of oil and laundering most of the proceeds, charges his lawyers say are ridiculous. His legal troubles have been widely seen as punishment for challenging Vladimir Putin, the former Russian president who remains as powerful as ever in his current role as prime minister. Putin's successor, President Dmitry Medvedev, has pledged to tackle corruption in the judicial system, and last year he urged Russian businessmen not to pay bribes to the courts in a rare acknowledgment of the scale of the problem. The judiciary also faced a crisis in 2008 when a senior judge revealed how the Kremlin exerts political pressure on legal rulings. But the anti-corruption drive championed by Medvedev, himself a former lawyer, has yielded few concrete results, and he has disappointed some rights activists by not reversing Putin's tough stance on the Khodorkovsky case. Khodorkovsky has already served six years of an eight-year sentence handed down in 2005 for tax evasion, most of that in a labor camp in the barren region of Chita, thousands of miles (kilometers) from his family, lawyers and the mainstream media in Moscow. In February 2009, Khodorkovsky was transferred back to the capital to face new embezzlement charges, which could keep him behind bars for 22 more years if he is again convicted. The end of his isolation in the labor camp was followed by a flurry of interviews, but Tuesday's hearing was his first chance to vent before the court. "This trial is political and corruptly motivated. It is driven by a desire to keep me from going free," he told a courtroom crammed with supporters and journalists. "It has also been motivated by a desire to appropriate the assets of the largest and most successful Russian oil company, Yukos." The charges in the case rest on allegations that Khodorkovsky and his partner Platon Lebedev embezzled all of the crude produced by their Yukos oil company from 1998 to 2003, amounting to some 350 million tons. Khodorkovsky argued that this would have been physically impossible, especially considering that the company continued to earn profits and pay dividends, and he entered a motion demanding that the prosecution demonstrate exactly how this could have happened. "To give you a crude analogy, your honor, the smoking gun in this case would have been incapable of firing," he told the presiding judge, Viktor Danilkin, who brushed off several efforts by the prosecution to interrupt Khodorkovsky. But Danilkin did not take kindly to the stunt with the jars of oil, and ordered bailiffs to remove them, rousing jeers and laughter from the gallery. "Is there gasoline in those jars?" Danilkin asked as he shouted for order. "I don't see anything funny about flammable liquids in a packed courtroom." Prosecutor Valery Lakhtin responded to the motion for clarity by rattling off the detailed list of charges against Khodorkovsky. The judge rebuked him for failing to address the point of the motion, but then dismissed it anyway, saying clarification of the charges is not appropriate to the advanced phase of the proceedings. Outside the courthouse, one of the lawyers for the defense, Vladimir Krasnov, said the day's theatrics were intended in part to reveal "the utter absurdity of this trial." Lakhtin, the prosecutor, declined to comment on the proceedings. Other lawyers for the defense said Khodorkovsky has prepared some 200 pages of testimony, which he will be reading out in the coming days until he finishes or is cut off by the court.