By Maria Tsvetkova
MOSCOW (Reuters) - Russia's Supreme Court ruled in favor of jailed former oil tycoon Mikhail Khodorkovsky on Friday in an appeal against his prolonged detention in the final months of his second trial last year.
The decision was a moral victory for Khodorkovsky, who was sentenced to remain in prison until 2017 in a December ruling condemned by Western governments and rights groups, but it will not lead to his release.
The Supreme Court overturned lower court decisions to keep the former Yukos oil company chief executive and his co-defendant Platon Lebedev in pre-trial detention from late August to November 2010, granting an appeal from their lawyers.
The appeal was based on legislation enacted early last year by President Dmitry Medvedev enabling suspects accused of some economic crimes to avoid pre-trial detention.
The ruling could boost the image of Medvedev, who has championed reform of a justice system marred by corruption and political influence but has achieved little progress.
Khodorkovsky said his case showed courts had continued to jail economic crimes suspects who should not be behind bars, calling it "systematic sabotage of the reforms announced by the president."
"While your decision, respected court, will not have a direct effect on my fate or that of Platon Lebedev, it will have fundamental importance," he told the three-judge panel.
His lawyer Vadim Klyuvgant, however, suggested the ruling was a cosmetic effort to show Medvedev's reforms were working and improve Russia's image.
"The situation is so crazy and so lacking in practical consequences that it was possible (for the court) to completely painlessly demonstrate that sometimes in Russia, even in this case, there are reasonable rulings."
The ruling did not mean Khodorkovsky should have been freed last year, because he was serving a prison sentence handed down in 2005 after an initial trial on fraud and tax evasion charges.
He had been set for release later this year but a Moscow judge sentenced him to six more years on December 30 after convicting him of multi-billion-dollar theft and money-laundering charges.
Supporters said Khodorkovsky's first trial was part of a Kremlin campaign to punish him for perceived challenges to Vladimir Putin, who was president at the time, and to tighten state control over Russia's oil reserves.
Once Russia's biggest oil producer, Yukos was bankrupted by back-tax claims after Khodorkovsky was arrested in 2003 and its assets sold off at auction, with its main production subsidiaries ending up in the hands of state-run Rosneft.
Khodorkovsky has appealed against his second conviction but hearings have not yet begun.
(Writing by Steve Gutterman; Editing by Thomas Grove and Andrew Dobbie)