French police have detained a Russian tycoon on suspicion of violating financial and sanctions restrictions.

French police have detained Russian taikan Alexei Kuzmichev and searched two of his properties in connection with alleged tax evasion, money laundering and sanctions violations. France's financial prosecutor said Tuesday that the searches took place at Kuzmichev's home in Paris and an estate in the Var region of the Mediterranean. Kuzmichev is still in custody but has not yet been charged. His lawyer declined to comment on the situation.

Kuzmichev, one of the founders of Russia's Alfa Bank, was sanctioned by the EU shortly after Moscow's invasion of Ukraine began because of his "well-established ties to the Russian president." According to the EU, Kuzmichev "actively supported materially or financially and benefited Russian persons responsible for the annexation of Crimea or destabilization of Ukraine." Kuzmichev's partners in Alfa Bank - Mikhail Fridman, German Khan and Pyotr Aven - were also sanctioned in the same EU ruling.

French customs officials seized the billionaire's 26-meter (86-foot) long yacht La Petite Ourse last year as part of the sanctions, sparking a legal fight between authorities and Kuzmichev. Forbes magazine names Kuzmichev, 61, who founded Alfa Bank with his colleagues in 1990, as the 61st richest man in the world with a total fortune of 5.3 billion pounds. After sanctions were imposed on him, Kuzmichev sold his shares in the bank last year to Andrei Kosogov, an Alfa Bank shareholder who was not sanctioned.

Kuzmichev is one of the few sanctioned Russian oligarchs left in Europe after the war in Ukraine.

His business partner Friedman, who is also under sanctions in Britain, returned to Moscow earlier this month, while Khan returned to Russia last year. Last week, London's high court rejected Friedman's request to spend thousands of pounds a month on the upkeep of his London mansion, which houses a collection of paintings worth 44 million pounds.

While some oligarchs support Vladimir Putin's invasion, Kuzmichev is one of the few major businessmen who have spoken out against the war, albeit cautiously. "My mother was Ukrainian, I have a huge number of relatives and friends there," Kuzmichev told the Russian website Forbes last year, adding that he agreed with Friedman, who said the conflict was a "tragedy" and war "can never be the answer. "

The Kremlin said Tuesday that Russia will be able to protect Kuzmichev's rights once Paris provides details of his case. "As far as I understand, he is a citizen of Russian Federation, so we should receive information about his detention through our diplomatic mission", Putin's spokesman, Dmitry Peskov, told reporters. "As soon as we receive information, and if the detainee wishes, we will of course help protect his rights as a Russian citizen. "