Putin Says Will Pardon Bitter Kremlin Critic Khodorkovsky

President Vladimir Putin announced Thursday that he would pardon ex-oil tycoon and bitter Kremlin critic Mikhail Khodorkovsky, a move that should see Russia's most famous prisoner freed after more than a decade behind bars.

The shock announcement could finally draw the curtain on the most notorious legal case in post-Soviet Russian history and came as Russia comes under even greater international scrutiny in the run-up to the Winter Olympic Games in February.

Khodorkovsky's decade-long imprisonment on embezzlement and fraud convictions in jails including a penal colony in Siberia has dented Russia's investment climate and become a symbol of the erosion of human rights under Putin.

Putin revealed after his marathon annual news conference that Khodorkovsky, 50, had for the first time written a request for a pardon, citing humanitarian circumstances as his mother is ill.

"I think given the circumstances we can take the decision and very soon the decree to pardon him will be signed," Putin said in televised comments.

Khodorkovsky's legal team and even his mother said they did not know if the former oil tycoon, who has been in prison since 2003, had asked for a pardon but Putin's spokesman told Agence France Presse the request had been personally signed by him.

He had been due to be released in August 2014 and is currently serving out his term at a penal colony in the remote town of Segezha in the northern Karelia region.

Russian prosecutors earlier this month had raised the menace of a third trial for Khodorkovsky on money laundering charges but this now looks unlikely.

Putin said that under Russian law a convict has to request a pardon before obtaining one, adding the 50-year-old Khodorkovsky had not done this until now.

"He did not do this and then quite recently he wrote such a document and addressed me with a request for a pardon," said Putin while referring to Khodorkovsky with the respectful patronymic form as Mikhail Borisovich.

"He has already been in detention more than 10 years, this is a serious punishment and he is referring to humanitarian circumstances as his mother is ill," said Putin.

Putin's announcement caught Khodorkovsky's legal team and family off guard.

"Until the legal team can meet with Mikhail Khodorkovsky, all previously given statements by his lawyers regarding him asking for a pardon should be considered invalid," said a statement on the Khodorkovsky website.

Khodorkovsky's mother Marina was quoted as saying that she also was not aware of her son's request but added that she supported "fully and completely" any of his decisions.

Kremlin spokesman Dmitry Peskov told Agence France Presse that the request had been personally "signed" by Khodorkovsky.

The pardon coincides with an amnesty for some prisoners in Russia that is also expected to include the jailed punks from anti-Kremlin rock group Pussy Riot.

Khodorkovsky has repeatedly indicated that he would not ask Putin for a pardon because that would be tantamount to admitting his guilt.

He occasionally joked bitterly that he would remain in jail indefinitely.

"It is hard for me to imagine the possibility of being released: 10 years in prison is not a joke," he told opposition weekly The New Times for which he wrote a column about his life in prison.

Rights activists and supporters have said that Khodorkovsky had been thrown into jail and found guilty in two separate trials for daring to finance political opposition to the Russian strongman.

Putin has denied that the tycoon's jail term was politically motivated but his statements have repeatedly betrayed a visceral animosity for the tycoon.

Just before Khodorkovsky was sentenced to a second term in prison in 2010, Putin said on television that "a thief must be in prison."

Khodorkovsky for his part frequently needled the president with his jabs from prison, saying famously that Putin loved only dogs.

Thursday's announcement caused a stir in Moscow and Russia's stock market recorded strong gains, with political figures and analysts saying it could not be overestimated.

"It's a landmark event," former finance minister Alexei Kudrin said on Twitter.

"His release is an event of a colossal significance," said Maria Lipman, an analyst at the Carnegie Moscow Center, noting that Putin no longer saw the tycoon as a threat.

"It is a declaration and confirmation of the fact that he is a master in his country and makes all the most important decisions himself."

Khodorkovsky was snatched off his corporate jet by special security forces in October 2003 shortly after Putin warned tycoons against meddling in politics.

He and his business partner Platon Lebedev were convicted of fraud and tax evasion in 2005. Several more managers also served time or fled the country.

After Khodorkovsky's Yukos oil company was broken up, state oil firm Rosneft snapped up most of its assets.

The tycoon has expressed sympathy for the Russian opposition but indicated that upon his release he would not go into politics, saying he would focus on civil society projects.