"And that is probably an underestimate," Thierry Debels, who has written a book on the Belgian dynasty's wealth, was quoted as saying.

That figure dwarfs the 12.4 million euro figure officially recognised by the royal household.

The palace was quick to respond, with a royal spokesman denying in a statement the billionaire claim which it dismissed as "fantasy".

"Eight years ago, the royal palace also denied another fantastical figure, which appeared in another book," the statement added.

The Belgian royal family has often been criticised in the Dutch-language Flemish press.

Analysts see such attacks as a Flemish move to scrap the royal family's residual political powers.

Dutch-speaking Flanders is the larger and richer of Belgium's two main linguistic groups.

The French-speakers of the southern Wallonia region fear that nationalists among their northern neighbours are moving towards independence.

AFP/Expatica