Former Russian tycoon: Vladimir Putin is a 'naked king' facing economic ruin and discord

Former Russian tycoon Mikhail Khodorkovsky warned Vladimir Putin on Thursday that the Kremlin chief was a "naked king" presiding over an economy that will weaken further, eventually provoking a battle between rival clans in Moscow.

"Putin with bare chest isn't a mighty leader: He is a naked king," Khodorkovsky, once Russia's richest man who was arrested in 2003 after falling foul of Putin only to be released in 2013, told an audience in London.

Khodorkovsky, who once controlled Russia's biggest oil company, said the Russian economy would weaken further and that eventually its weakness would provoke a battle between the powerful clans which dominate Russia.

In a message which likely to anger the 62-year-old Kremlin chief, the former tycoon also called on the West to build ties with Russian opposition groups in expectation of an end to the Putin era.

"Tomorrow when the regime changes you will have to build relationship and you will have very little time," said Khodorkovsky, 51. "I know what I'm saying as I witnessed two revolutions in Russia."