An Arkhangelsk region court on Wednesday turned down ex-Yukos executive Platon Lebedev’s parole petition.
The judge said “the aims of the two sentences handed down by Moscow courts had not yet been achieved.”
A lawyer for Lebedev said his client would appeal.
Human rights activists were quick to criticize the decision.
“I am disappointed,” Lev Ponomaryov of the For Human Rights group said.
“It was not a decision based in law. I believe the judge was subjected to pressure.”
Moscow Helsinki Group head Lyudmila Alexeyeva said the Lebedev ruling was predicable and that Khodorkovsky’s petition would be rejected as well.
“Khodorkovsky’s request will be turned down just the same because such decisions are not made in court but at much higher level,” she said.
But Judge Nikolai Raspolov said he had acted independently.
"It was absolutely my own decision," he said.
Lebedev and his business partner Khodorkovsky, once Russia's richest man, were sentenced to stay in jail until 2016 in a second trial in December. They were first jailed in 2003 on tax evasion charges.
They have both denied all the charges against them, claiming that the Yukos case was revenge by Russia's powerful Prime Minister Vladimir Putin for Khodorkovsky's sponsorship of opposition groups in the early 2000s. The Russian authorities have categorically denied the claim.
Khodorkovsky asked for parole last month but the court refused to consider it. Putin earlier likened him to American gangster Al Capone and said “a thief belongs in jail.”