Russia’s annexation of Crimea and the economic sanctions that followed do not appear to have stopped some of Ukraine’s richest men from still doing business on the peninsula, a new investigation purports to show.

The richest Ukrainian, Rinat Akhmetov, the tycoon Vasyl Khmelnytsky and the multimillionaire brothers Serhiy and Andriy Klyuev are alleged to still be operating their businesses in Crimea, despite Ukrainian, U.S. and European Union sanctions.