The Russian billionaire owner of Monaco football club, Dmitry Rybolovlev, has been placed under formal investigation in connection with a major fraud case.
It involves a Swiss art dealer from whom Mr Rybolovlev bought a series of masterpieces, triggering a long-running separate legal battle.
Officials have been investigating claims that Mr Rybolovlev tried to influence Monaco police officers.
No charges have been announced. Mr Rybolovlev denies any wrongdoing.
Under Monaco’s criminal system, which mirror France’s, a suspect is placed under investigation by a magistrate, who then determines whether there is sufficient evidence to hold a trial.
It it not clear what specific charges, if any, Mr Rybolovlev may face if the case proceeds.
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The long-running dispute involves Swiss dealer Yves Bouvier, whom Mr Rybolovlev accuses of defrauding him of about $1bn (£760,000).
He had purchased 38 works of art from Mr Bouvier over the course of a decade, the prices of which he claims were deliberately inflated. Mr Bouvier denies those accusations.
One of those paintings is Salvator Mundi, believed to be by Leonardo da Vinci, which last year became the most expensive painting ever sold. Mr Rybolovlev auctioned it at Christie’s in New York for $450m (£341m).
Three other people were also placed under formal investigation alongside Mr Rybolovlev.
All the accused have been released while investigations continue, and all deny wrongdoing.
Mr Rybolovlev’s lawyers told Reuters news agency that their client was not restricted from travel.
“We particularly insist on the fact that, at this stage, Mr Rybolovlev is presumed innocent,” they said.
Russian AS Monaco owner Rybolovlev under formal investigation