Khodorkovsky, who was sentenced to nine years in prison for fraud and tax evasion in May, said he believed Sechin was behind the two-year attack on Yukos, rather than Sibneft owner Roman Abramovich, as his business partner Leonid Nevzlin has claimed.
While many observers have suggested that Sechin was a major player in the Yukos affair, Khodorkovsky has never before publicly said who he believes to be behind the attack on him and his Yukos empire.
"Roma Abramovich, to put it mildly, is not St. Peter. But the organizer and the motor behind the Yukos affair was in fact Igor Sechin, one of his competitors in the fight for influence over Putin," Khodorkovsky said in an interview published in Thursday's Vedomosti newspaper.
Sechin is seen as a leading member of the siloviki clan that rose to power along with Putin. He is also chairman of Rosneft, the state-owned oil company that took over Yuganskneftegaz, Yukos' main production unit, last year.
The Kremlin on Thursday denied Khodorkovsky's claims. "These accusations are groundless and have nothing to do with reality," Kremlin spokesman Dmitry Peskov said, Bloomberg reported. "Neither Sechin nor the leadership of the presidential administration had any connection to the court or tax cases."
In a March 2003 interview several months before his arrest, Khodorkovsky hinted at a growing power struggle with state-owned companies such as Rosneft and pipeline operator Transneft, and warned there could be an attempt to take over Yukos.
Nevzlin, who now lives in Israel and is wanted by Russian prosecutors, claimed in April that Abramovich was one of a "group of plotters" who tried to wrest Yukos away from its shareholders.
Nevzlin said that Abramovich, whose Sibneft oil major pulled out of a planned merger with Yukos in November 2003, had tricked Khodorkovsky into believing that Putin had approved the sale of a significant minority stake in the merged company to a U.S. oil major.
The proposed sale is believed to have been a major factor behind the Kremlin's attack, because the deal would have given Khodorkovsky billions of dollars to potentially spend on political projects, while making his company untouchable.
Khodorkovsky said that he and his business partners should not have trusted Abramovich, but said Abramovich was not to blame.
"Abramovich, of course, didn't do anything to help me or my partners, but at the end of the day, he is a friend of Putin's and not of mine. We should not have been counting on him," he said.
Sibneft spokesman John Mann said on Thursday, "I'm not in a position to comment on [Abramovich's] personal friendships. But I'm sure they have a good working relationship, as President Putin does with all regional governors."
Khodorkovsky said the attack on Yukos showed that Kremlin officials were pursuing their own business interests. "Today, we clearly see that structures of executive power are motivated by private business interests no less than they were in the 1990s," he said. "The Yukos case has not changed anything. On the contrary, the level of cynicism has grown and it has become clear that the foundation of contemporary Russian capitalism is the rule of crude force."
Khodorkovsky's interview came three days after his latest political commentary was published as a letter in Monday's Vedomosti. In the letter, he warned that the current regime would have to make way for leftist forces or face mass unrest.
In Thursday's interview, Khodorkovsky said he believed he would be freed in three or four years, suggesting that he thought change was coming. "I am sure that the sentence will not just be lightened, but that it will be overturned by the Supreme Court in about three to four years," he said.
He said Kremlin officials did not have "the power, the energy or the conviction in their own righteousness" to launch a similar attack on another oligarch, but said that did not mean they should not fear attacks on their property by others involved in the continuing asset carve-up.
"Now, even the Kremlin is talking about the exclusively selective use of the law in the Yukos case and proposing some kind of non-aggression pact with business," he said.
"I can't guarantee that none of the so-called oligarchs -- major ones or lesser ones -- won't be imprisoned or killed. The Kremlin is not the only player."
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