Russian prosecutors filed a lawsuit against sanctioned billionaire Andrey Melnichenko, as President Vladimir Putin increases pressure on wealthy Russians to repatriate their assets from abroad.

The claim against Melnichenko, founder of Russia’s biggest steam coal miner Suek JSK and fertilizer maker EuroChem Group AG, was filed on Aug. 17 in the Siberian city of Krasnoyarsk. It targets Melnichenko, Suek and two other companies, according to the filing on the court’s website, which didn’t provide further details.

Following Putin’s invasion of Ukraine and sanctions that have hit the economy, the Russian president has slammed industrialists and other rich Russians who maintain wealth abroad and called for them to repatriate assets.

Last week Putin asked the government and lobby groups to accelerate the transfer of businesses to Russian jurisdiction. While Suek is based in Russia, EuroChem, which isn’t involved in the case, is registered in Switzerland while holding major assets in Russia.

The case relates to energy assets that companies linked to him purchased in 2018 from businesses connected to former government minister Mikhail Abyzov, who was arrested and charged in 2019 in an alleged embezzlement case, the RBC newswire reported.

Melnichenko received the claim, his spokesperson said. A hearing is scheduled for Sept. 7, according to court’s website.

Worth an estimated $13 billion according to the Bloomberg Billionaires Index, Melnichenko now resides in the United Arab Emirates after living for many years in Europe.

He was sanctioned by the European Union and the US following Russia’s attack on Ukraine. He then withdrew as a beneficiary of a trust that controls stakes in the companies he founded. That left his wife — Serbian singer Sandra Nikolic, an EU citizen - as the beneficiary, but she was later sanctioned too.

According to Putin, Russian businessmen who have moved their assets and families abroad must realize that they will remain “second-class strangers” despite having aquired the titles of “earls, peers and mayors,” he told lawmakers in February.