President Vladimir Putin on Friday signed a decree granting a pardon to Russia's former richest man Mikhail Khodorkovsky, allowing his release after over a decade in prison, the Kremlin said. "Guided by humanitarian principles, I decree that Mikhail Borisovich Khodorkovsky... should be pardoned and freed from any further punishment in the form of imprisonment. This decree comes into force from the day of its signing," said the decree signed by Putin and published by the Kremlin. In a shock remark after his annual marathon news conference on Thursday, Putin said Khodorkovsky had asked for clemency on humanitarian grounds as his mother was ill. The Kommersant broadsheet, citing unnamed sources, said on Friday Khodorkovsky had made the decision to seek a pardon after a recent meeting with representatives of Russia's security services who had raised the menace of a third trial against him. The prospect of the imminent release of Khodorkovsky, who has been in jail since 2003, caught his legal team and even family off guard. "God, he had mercy!" exclaimed mass-circulation newspaper Moskovsky Komsomolets in a banner headline on Friday. Economists and political analysts put the announcement down to Kremlin's bid to improve its dismal rights record and international image ahead of the Winter Olympic Games in February. The former chief of Yukos oil company, once Russia's richest man, had repeatedly said he would not ask Putin for a pardon because it would be tantamount to admitting guilt.