* Khodorkovsky was jailed after falling out with Putin
* Sentence reduced, now due to be freed in 2014
* Putin says no personal grudge against former oil tycoon
* But Russian protest leader Navalny faces new charges
By Alexei Anishchuk and Alissa de Carbonnel
Dec 20 (Reuters) - A Russian court reduced former oil tycoon Mikhail Khodorkovsky's jail sentence for embezzlement by two years on Thursday, clearing the way for one of President Vladimir Putin's fiercest critics to walk free in October 2014.
Khodorkovsky, once Russia's richest man, is serving a 13-year sentence near the Arctic circle on charges of multi-million dollar tax evasion and money laundering, a punishment seen by Putin's critics as a politically-motivated act of revenge.
One of the young tycoons who built fortunes after the Soviet Union's 1991 collapse, Khodorkovsky, now 49, had appeared to defy calls by the president for rich businessmen, or oligarchs, to stay out of politics.
After his arrest, in 2003, his Yukos oil company was broken up and sold off, mainly into state hands.
Once freed, some believe he could unite Russia's fragmented opposition to pose a serious challenge to Putin, though he has played down such speculation.
Putin once dismissed Khodorkovsky's case by saying thieves must sit in jail. But asked about the ruling on Thursday, he said he bore no grudge against him, saying he had not played any role in the court's decision.
"As for Mikhail Borisovich (Khodorkovsky), there was no personal persecution ... This is a purely an economic crime. The court took its decision," Putin told his annual news conference.
"As regards my opinion that a thief must sit in jail, who is against that? Should he walk the streets?," he said.
Putin said Khodorkovsky's sentence was reduced as a result of a liberalisation of Russia's criminal laws.
Under the ruling, his business partner Platon Lebedev would also be released early, in July 2014.
The two men's jailing during Putin's first spell as president from 2000 until 2008 was widely criticised abroad.
Kremlin critics regard the two men as political prisoners - a charge the Russian government denies.
CHARGES LEVELLED AT ANOTHER PUTIN FOE
Some Putin critics have drawn comparisons between Khodorkovsky's case and criminal charges filed against Alexei Navalny, the most prominent leader of large street protests against Putin's nearly 13-year rule.
Investigators charged the anti-corruption blogger and his younger brother Oleg on Thursday with being involved in a scheme to cheat a mail transport company out of 55 million roubles ($1.79 million).
Navalny, 36, already faces up to 10 years in jail if found guilty of separate earlier charges of theft from a state timber company.
He denies any wrongdoing and says the accusations are intended to persuade him to stop his opposition activities.
Civil rights activists said the new charges against Navalny outweighed the news about Khodorkovsky and were a reminder of how far Putin has been ready to go to crack down on dissent since he began a third Kremlin term in May.
"This is typical Kremlin good-cop, bad-cop tactics that fully reflects Vladimir Putin's ways," human rights activist Lev Ponomaryov told Reuters.
CHANGES IN THE LEGAL CODE
Opposition leaders have said in the past that the Kremlin would allow Khodorkovsky's release only when it was certain he was no longer a political threat to Putin.
Putin says the judiciary is independent, but Khodorkovsky's imprisonment was interpreted by the former KGB spy's opponents as a warning to wealthy tycoons to stay out of politics. It was also seen as the beginning of a Kremlin drive to increase state control over lucrative oil investments.
Defence lawyers for Khodorkovsky and Lebedev had argued for their sentences to be cut, saying the two men were charged twice with the same crime when they were convicted in a second trial in December 2010.
But defence lawyer Yuri Shmidt said the court had based its decision solely on the retroactive entry into force of changes in Russia's criminal law.
Pouring cold water on the ruling, Shmidt said he would not believe it until Khodorkovsky was released.
"Maybe yet another case against him will appear or something else will happen - until the day he leaves the penal colony it's too early to say," Shmidt said.
Lebedev and Khodorkovsky have waged court battles for years against their sentences, in Russia and at the European Court of Human Rights. They have repeatedly hoped to secure early release but their hopes have been dashed on previous occasions.
"This should not be seen as an act of humanitarianism or mercy from the authorities," Pavel Chikov, head of the human rights organization Agora, told Reuters.