MOSCOW:Russia's Supreme Court said Sunday it would hear an appeal against the second conviction of jailed former oil tycoon and fierce Kremlin critic Mikhail Khodorkovsky.

The surprise announcement means that Russia's former richest man - behind bars since 2003 - could walk free years before his second sentence on money laundering and embezzlement charges expires in 2016. The country's highest court posted the decision on its website without explaining which part of Khodorkovsky's conviction it would review or when the hearing would take place.

"This means that the appeal will be reviewed at a special session of the judicial board," Khodorkovsky's attorney Vadim Klyuvgant told the Interfax news agency. "If they follow the law, the judicial board has no choice but to let Khodorkovsky and (co-defendant Platon) Lebedev free," he added.

The decision represents a rare victory for a man who built an empire from the now dismantled Yukos oil company to become not onlyRussia's most powerful oligarch but also one of President Vladimir Putin's most potent foes.

Khodorkovsky openly funded parliamentary opposition parties while free and lobbied heavily for his oil interests at the Kremlin - often running into resistance from state firms.

He and Lebedev - head of the former Menatep bank that formed a part of Khodorkovsky's conglomerate - were jailed in 2004 on fraud and tax evasion charges.

Shortly before their scheduled release, their stay in jail was extended during a second and controversial trial in 2010 in a move that drew strong condemnation from the West.

The prospect of Khodorkovsky's possible release has the potential to boostRussia's flagging opposition movement as well as improveMoscow's deteriorating relations with theUnited States.