ZURICH (REUTERS) - Former Russian oligarch Mikhail Khodorkovsky has submitted a request to settle permanently in Switzerland, a spokesman said on Monday.

The 50-year-old former oil tycoon was granted a three-month Schengen visa by Switzerland at the end of last year and arrived by train in Basel from Berlin at the start of January to take his two youngest sons back to school.

A spokesman for Mr Khodorkovsky confirmed he had submitted a request for permanent residency in Switzerland, but she declined to give any further details on where exactly he was hoping to make his home.

Mr Khodorkovsky's second wife Inna has a home in Geneva, where several of his companies had operations, the Swiss daily Le Matin has reported.

Once Russia's richest man, Mr Khodorkovsky was jailed in 2003 for fraud and tax evasion. He was seen by many as a political prisoner, the highest-profile victim of President Vladimir Putin's campaign to rein in the "oligarchs" who had made fortunes snapping up assets in the chaotic years of Boris Yeltsin's rule following the collapse of Soviet communism.

Mr Khodorkovsky, who was released from a Russian prison camp near the Arctic Circle last December, has spent much of the last few months travelling.

On Sunday, he addressed thousands of people in Kiev and accused Russia of being complicit in police violence against protestors.