Former oil tycoon Mikhail Khodorkovsky's business partner Platon Lebedev walked free from prison on Friday after Russia's Supreme Court ordered his early release.

The 57-year-old had served 10-and-a-half years of his sentence for fraud, tax evasion and money laundering before the court ordered his release on Thursday. His sentence had been due to end in May

"Platon Lebedev left the prison colony... in the Arkhangelsk region around 10:00 pm Moscow time (1800 GMT)," a spokesman for the prison service told the RIA Novosti news agency.

Khodorkovsky was released last month after receiving a pardon from President Vladimir Putin on humanitarian grounds and left Russia immediately afterwards. He is currently in Switzerland with his family.

Lebedev left the prison colony after being met by his eldest daughter Lyudmila and his son Mikhail, his lawyer Vladimir Krasnov told Khodorkovsky's official website.

"I am just bursting inside. I congratulate everyone on this news," Krasnov said.

Interfax news agency said earlier that Lebedev's twin brother Viktor had gone to meet him in the penal colony.

The Supreme Court did not give an official reason for cutting short Lebedev's prison term.

The Supreme Court upheld a $550 million (400-million-euro) tax claim against Khodorkovsky. Lebedev is also understood to owe tax arrears.

Observers attributed the surprise release of Putin's top critic Khodorkovsky to Kremlin attempts to improve Russia's international image ahead of the Olympic Games that begin in Sochi on February 7.

The cloak-and-dagger operation was quietly agreed between the Kremlin and German diplomats including former foreign minister Hans-Dietrich Genscher.

The release drew the curtain on the highest profile criminal case in post-Soviet Russia which has harmed the country's investment climate and become a symbol for the selective persecution of Kremlin foes under Putin.

Russia in December also pardoned international Greenpeace activists awaiting trial for a protest against Arctic drilling and the two Pussy Riot members who were serving two-year sentences for an anti-Putin performance in a church.

Lebedev was head of the former Menatep bank that formed part of Khodorkovsky's business empire.

He was arrested in July 2003. He was Khodorkovsky's co-defendant in two highly controversial trials, which saw both convicted on charges of fraud, tax evasion and money laundering.

But supporters of the accused said they were being punished for daring to fund the opposition.

Khodorkovsky has said that the decision to imprison and then release him was taken personally by Putin, although he said in December that he did not hold a grudge against the president because his family was spared.

The European Court of Human Rights had said that the trials were unfair, but did not call them politically motivated.

Lebedev had been serving his sentence in a penal colony in the far-northern Arkhangelsk region, around 650 kilometres (400 miles) from Moscow.

His defence team repeatedly complained that there was inadequate medical care for his health problems.