French police detained Russian billionaire oligarch Alexei Kuzmichev on Monday, in an investigation into money laundering, tax fraud and violations of international sanctions, according to Politico.

As part of a preliminary probe by France’s anti-corruption office (OCLCIFF), police on Monday carried out multiple searches at several locations in France, including Kuzmichev’s property in Paris, a spokesperson for France’s National Financial Prosecutor’s Office (PNF) confirmed to Politico.

Kuzmichev was detained Monday and remained in custody on Tuesday.

According to French daily Le Monde, Monday’s raids included more than 60 officers and Kuzmichev’s villa in Saint-Tropez was also searched.

Kuzmichev, a shareholder of Alfa Group, one of Russia’s largest private investment firms, was sanctioned by the EU along with several other Alfa Group shareholders after Russian President Vladimir Putin launched his full-scale invasion of Ukraine last year. The EU considers Kuzmichev “one of the most influential persons in Russia,” with close ties to Putin and the Russian regime.

Last year, Russian billionaire Mikhail Fridman — another Alfa Group shareholder — was also detained in London.