Top Kremlin critic Mikhail Khodorkovsky is seen on a screen as he speaks via live video conference with journalists at the Open Russia movement office in Moscow on December 9, 2015. (AFP)
Russian investigators today charged ex-oil tycoon and Kremlin critic Mikhail Khodorkovsky with organising the 1998 murder of a mayor in Siberia, ratcheting up their campaign against the exiled former Yukos boss.
"As a result of investigative work, we managed to obtain new information and in light of this, it was decided on December 11, 2015, to prosecute Mikhail Khodorkovsky as a defendant for the organisation of murder," Russia's powerful Investigative Committee said in a statement.
Investigators announced in June that they were reopening a criminal probe into the 1998 murder of Vladimir Petukhov, the mayor of oil-producing city Nefteyugansk, saying that Khodorkovsky -- then the head of the now-defunct oil giant Yukos -- may have ordered the killing.
Khodorkovsky, who now lives in London, has claimed that the new probe into the mayor's murder, for which his former Yukos security chief is already serving a life term, was ordered personally by President Vladimir Putin.
The Investigative Committee said today that Khodorkovsky would be put on a wanted list "in the near future."
Khodorkovsky, once Russia's richest man, spent a decade in prison on charges of tax evasion, fraud and embezzlement, which he blames on a political vendetta by Putin.
In late 2013 he was unexpectedly released and flown out of the country after a presidential pardon but after intially pledging to stay out of politics he has once again become an outspoken critic of Putin.
Russian prosecutors on Thursday demanded that Khodorkovksy be investigated for allegedly calling for "regime change".