BERLIN - German authorities are conducting nationwide raids of properties linked to Mr Alisher Usmanov as part of a probe against the sanctioned Russian billionaire.

Two dozen sites in Bavaria, Baden-Wurttemberg, Schleswig-Holstein and Hamburg are being searched, Munich prosecutors said in statement.

They are probing a Russian citizen who is on the sanctions list.

While no names where disclosed, the target is Mr Usmanov, a person familiar with the matter said.

Hundreds of officers from various tax and police departments are involved.

A spokesman for Mr Usmanov did not immediately reply to an e-mail seeking comment.

Usmanov is being investigated for sanctions violations because he allegedly kept and paid security staff to look after a luxury compound in Bavaria, according to the statement.

The staff members are also being investigated.

Mr Usmanov, 69, owns a major stake in USM, a Russian investment group with holdings in Metalloinvest, one of the world's largest iron ore producers, and telecommunications company MegaFon.

He has a fortune of US$17.8 billion (S$25 billion), according to the Bloomberg Billionaires Index.

German authorities previously impounded Mr Usmanov's superyacht Dilbar after determining it was legally owned by his sister, who is also subject to Western sanctions over the war in Ukraine.

He appealed against the European Union sanctions at the EU's general court in April. BLOOMBERG