BRUSSELS (AP) — Belgian authorities have searched the home of a member of one of France's wealthiest families in what local media report is an investigation in three European countries into suspected tax fraud and money-laundering.

Assistant prosecutor Frederic Bariseau told The Associated Press on Wednesday that "the search took place at the residence of Patrick Mulliez."

The Mulliez family runs an empire worth tens of billions of dollars, with brands including supermarket group Auchan, sporting goods retailer Decathlon and home improvement chain Leroy Merlin.

Bariseau said that Tuesday's search was done on the basis of an international warrant and that material had been seized. He declined to provide details. The warrant was for search purposes only and no arrest was made.

Mulliez's home is in Nechin, just across the border from Roubaix in France, where the Mulliez group has its headquarters.

Belgian business daily l'Echo said that searches of Mulliez properties were also conducted in France and Luxembourg.

Bariseau said the search was a one-off, given the nature of the warrant, but that "based on their findings, the French authorities could ask us to do more."

The author of a book on the Mulliez family and its business, investigative journalist Bertrand Gobin, said that "on a demographic level, it has no parallel in Europe."

"Usually at this level companies are on the stock exchange. The Mulliez have self-funded their expansion," he said.

He said that the family's roughly 700 adult members control the companies through a "cascade" of holding companies.

"The Mulliez are experts in tax optimization," he said, adding that they had - so far - worked hard to minimize their tax burden while staying on the right side of the law. "This would be the first time they've been nabbed."

Satter reported from Paris.