MOSCOW (REUTERS) - Jailed former oil tycoon Mikhail Khodorkovsky has asked Russia's Supreme Court to release him and overturn a sentence he said was one of many "faulty rulings" that have spurred opposition to President Vladimir Putin.

Khodorkovsky, who was Russia's richest man as head of the Yukos oil company before his arrest in 2003 and sentencing in 2005 for tax evasion and fraud, read out his appeal in a video link from a prison colony near the Arctic Circle.

"In this case, the usual mantra that everything is legal and well-grounded just won't do," said Khodorkovsky, seen by some Kremlin critics as a potential opposition leader.

Describing his case as political, he said: "Faulty court rulings have already become a catalyst for the protest movement (against Putin). A growing part of society is demanding ... to be able to live and not be afraid."

The Supreme Court is expected to rule on Tuesday whether to cut Khodorkovsky's sentence, and that of his former business partner Platon Lebedev, after their lawyers argued that their arrest was illegal and the length of their prison sentences unfair.

Khodorkovsky, 50, is not expected to be released more than a year ahead of time. But the former businessman, who wore a black shirt and was handcuffed, said: "It always has been, and remains, important for me to get justice in my homeland."

Khodorkovsky's US$40-billion (S$50.95 billion) business empire was broken up and sold off, mainly into state hands, after his arrest and subsequent sentencing in 2005.

He had fallen out with Mr Putin by funding political parties other than the main pro-Kremlin party and suggesting some oil deals involving the state were corrupt.

Many foreign investors saw Khodorkovsky's jailing as a turning point in Mr Putin's 2000-2008 presidency, giving hardliners the upper hand and ultimately increasing their control over the economy.

Investors said his release would be a positive sign although they are more concerned about the treatment of opposition leader Alexei Navalny, who is appealing against a five-year jail term after being convicted in July of theft.

In their first trial, Khodorkovsky and Lebedev were sentenced to nine years in prison, later reduced to eight, for fraud and tax evasion. They both pleaded not guilty.

More charges were brought against them and, found guilty of money-laundering and theft in 2010, their sentences were extended until 2017. They were later reduced to 2016 on appeal and then to 2014. Khodorkovsky is due for release in October 2014, and Platonov in July next year.

The European Court of Human Rights last month rejected suggestions that the case against Khodorkovsky had been politically motivated but found that the initial trial was unfair and the 2005 sentencing was unjustified.