Moscow:
Russia's supreme court on Tuesday began hearing an appeal by jailed former oil tycoon Mikhail Khodorkovsky against his second conviction which supporters say was ordered by the Kremlin.
Russia's former richest man, who has been behind bars since 2003, spoke via video link from his remote prison colony in northwestern Russia at the appeal hearing, an AFP correspondent reported.
The Moscow-based supreme court is to rule whether his second sentence for money laundering and embezzlement should be lifted before he is due to walk free in October 2014.
Khodorkovsky's defence team argued in the appeal that he and his business partner Platon Lebedev were convicted in 2010 on charges that were known to be false and that were invalid from the start.
In a statement to the court by the video link, Khodorkovsky denounced what he said was the use of Russian prosecutors and investigators as an "instrument of domestic politics in Russia".
"The result is catastrophic," said Khodorkovsky, who was shown on the video speaking behind a mesh grill wearing his laminated prison identity card.
"We are not talking about implementing the law, we are talking about a readiness to sacrifice the reputation of the legal system for the sake of a new prison sentence for an opponent of the authorities," he added.
"For me, it was and is always important to obtain justice in the motherland. Therefore we are all waiting for your decision," he told the judge.
In a surprise decision in May, the supreme court agreed to hear the appeal, which was submitted in March. It has not said which of Khodorkovsky's multiple convictions it would review.
Prosecutors on Tuesday asked the court not to shorten the sentences of Khodorkovsky and Lebedev. It was not immediately clear if the court would deliver its verdict on Tuesday.
Khodorkovsky and Lebedev -- head of the former Menatep bank that formed a part of Khodorkovsky's conglomerate -- were jailed in 2005 on fraud and tax evasion charges. Khodorkovsky turned 50 in jail this year, while Lebedev is 56.
Shortly before their scheduled release, their stay in jail was extended until 2017 during a second controversial trial in 2010 in a move that drew strong condemnation from the West.
Their sentences were then reduced by the Moscow city court and the men are scheduled to be released in 2014.
However some activists have expressed fear that new charges could yet be brought against Khodorkovsky as the Kremlin considers him such a dangerous potential opponent.
Khodorkovsky's supporters have long argued both sets of charges were trumped up by the state to punish him for daring to finance political opposition to President Vladimir Putin and ridiculed the circumstances of the second trial.
Putin, who has never made a secret of his dislike of Khodorkovsky, said even before the verdict in the second trial was announced that "a thief should be in prison," drawing criticism that he was interfering in the process.
Khodorkovsky is being held in a prison colony in Karelia in northwest Russia, while Lebedev is in the far north Arkhangelsk region.
In July, the European Court of Human Rights ruled the men's first trial had been unfair but said that the judge was impartial.
Pro-opposition observers link the Khodorkovsky case to a general crackdown on the opposition under Putin which last month saw protest leader Alexei Navalny handed a five year sentence in an embezzlement case.