Belgian authorities are investigating money-transfer fintech Wise for its controls around suspicious transactions worth over €500 million ($577 million) across 30 European countries. The current investigation only concerns the fintech’s EU operations, but the company has a history of fines for weak financial controls in several regions, including the U.S. and the Middle East.

The Bureau of Investigative Journalism, which broke the story on June 1, said the investigation was opened last year. Belgian prosecutors had spotted that “Wise accounts had featured in hundreds of requests for cross-border help in criminal proceedings from more than 30 countries across Europe. The transactions concerned amounted to half a billion euros,” they wrote.

Ruth Prickett graduated from Cambridge University with a BA hons in History and has specialized in business and finance journalism for the past 20 years. She was editor of Financial Management, the magazine...