Among the few ships seized is the superyacht Amore Vero, which is linked to the chief executive of Russian state oil giant Rosneft Igor Sechin.
The vast white vessel worth over 100 million euros, with a swimming pool that can be transformed into a helipad, was seized by French customs in the port of La Ciotat outside Marseille last March.
Industry newspaper SuperYacht Times confirmed other seizures including Amadea, a $300 million ship owned by oligarch Suleiman Kerimov and seized in May by authorities in Fiji on behalf of the United States. It has been impounded in San Diego, California.
Another big catch was Russian oligarch Viktor Vekselberg's $90 million superyacht Tango in Mallorca, Spain, last April.
The US last month unveiled criminal charges against two men who it said sought to protect Vekselberg's vessel from seizure.
And British authorities in March detained a Russian-owned $50 million superyacht, the Phi, docked at London's Canary Wharf.
The situation is further complicated because many yachts avoid the Russian flag, while oligarchs often hide behind front companies to cover their tracks.
The Phi, for example, is registered to a company based in the Caribbean nation of Saint Kitts and Nevis and sails under a Maltese flag.
But Britain's National Crime Agency anti-kleptocracy unit said its ultimate owner was a Russian businessman. The Financial Times reported last March that it belonged to Vitaly Vasilievich Kochetkov, a telecom oligarch.
