Former Russian tycoon
Mikhail Khodorkovsky is due to walk free in August of next year after
his latest prison sentence was cut by two months.
The supreme court reduced the sentences of Khodorkovsky and Platon Lebedev by two months at an appeal hearing.They were convicted - while serving time for tax evasion - of stealing oil and laundering money in 2010.
The European Court of Human Rights has criticised the trials, while rejecting claims they were politically motivated.
Lawyers for the two men were asking for their second convictions to be overturned, a request resisted by prosecutors.
The court upheld the sentences but reduced each man's sentence by two months, meaning Khodorkovsky, 50, should walk free in August next year, with Lebedev due for release a few months earlier.
Speaking via video link from his penal colony in Russia's northern region of Karelia, Khodorkovsky, the former head of the Yukos oil company, repeated his assertion that Russia's legal authorities were politically led.
"Beginning with the Yukos case, the prosecutors and after them, the Investigative Committee, alongside TV, have become the chief instruments of domestic politics," he said in his statement.
Once the country's richest man, Khodorkovsky was arrested in 2003 and convicted of tax evasion two years later. At the time of his arrest, he was seen as sympathising with liberal opposition forces, opposed to Russia's powerful President Vladimir Putin.
Khodorkovsky's parents were in court for the appeal hearing.
His mother, Marina, dismissed the judges as "newscasters in black robes" while his father, Boris, said he hoped the whole verdict would be annulled.