By Tatyana Makeyeva
SEGEZHA, Russia, Dec 20 (Reuters) - Mikhail Khodorkovsky, once Russia's richest man, left prison on Friday after a pardon from President Vladimir Putin ended a decade in jail that many saw as the fallen oil tycoon's punishment for daring to challenge the Kremlin.
His lawyer and a prison official said Khodorkovsky was free, a day after Putin unexpectedly announced he would release one of his most powerful critics. A government source said the move could deflect criticism over Putin's human rights record as Russia prepares to host the Winter Olympics in February.
"He has left the camp. That's all I can say," lawyer Vadim Klyuvgant told Reuters by telephone. A prison official, also reached by telephone, confirmed that. Journalists outside the prison deep in the sub-Arctic forest did not see Khodorkovsky.
Putin surprised Russians and cheered the business community by announcing he would free the 50-year-old businessman because his mother was ill. Investors said it could ease entrepreneurs' fears of the Kremlin exploiting the courts for political ends.
In a presidential decree signed on Friday, Putin said he was "guided by the principles of humanity".
Putin had said after a four-hour, end-of-year news conference on Thursday that Khodorkovsky asked for clemency.
His lawyers said they were checking that with their client. He was scheduled for release next August but supporters had feared the sentence might be extended, as it was once before.
Reporters waiting outside Penal Colony No. 7 at Segezha, near the Finnish border, 300 km (200 miles) south of the Arctic Circle, did not see Khodorkovsky leave. He has spent the past few years working in the camp, in an area that was once a notorious part of Stalin's Gulag system of labour camps.
Khodorkovsky came to represent what critics say is the post-Soviet Kremlin's continued misuse of the judicial system, curbing the rule of law, and of its refusal to permit dissent.
The authorities deny this, saying judges are independent and that Putin has not cracked down on opponents. The president has, however, singled Khodorkovsky out for bitter personal attacks in the past and ignored many calls for his release.
Thursday's surprise announcement underlined Putin's confidence that he has reasserted his authority and is in full control of Russia after seeing off street protests.
He said two members of the Pussy Riot protest group will also be freed, under an amnesty passed by parliament this week.
Khodorkovsky has been in jail since his arrest in October 2003 in what supporters say was part of a Kremlin campaign to punish him for political challenges to Putin, gain control of his oil assets and warn other tycoons to toe the line.
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The oil baron fell out with Putin before his arrest as the president clipped the wings of wealthy "oligarchs" who had become powerful during the chaotic years of Boris Yeltsin's rule following the collapse of Soviet communism.
His company, Yukos, was broken up and sold off, mainly into state hands, following his arrest at gunpoint on an airport runway in Siberia on fraud and tax evasion charges.
Yukos' prize production asset ended up in the hands of state oil company Rosneft, which is now headed by Putin ally Igor Sechin.
Russian shares initially rose after Putin's announcement on Thursday but later settled back.
A sustained rally would require "a consistent track record of implementation of market-friendly reforms - in particular, of steps to improve the judicial system, so that decisions are more predictable and property rights better protected," a Moscow-based economist at an investment bank said.
Putin has staked a great deal of personal prestige on the Winter Games at Sochi on the Black Sea and is under fire abroad over a law banning the spread of "gay propaganda" among minors.
A government source said the pardons would deprive Western critics of a cause: "I think the decision to free Pussy Riot and Khodorkovsky was taken just before the Olympic Games so that they will not be able to wield this banner against Putin."