Economist Alexandre Lamfalussy, one of the founding fathers of the European single currency, died on Saturday at the age of 86, Belgian media reported on Monday.
No other details were immediately available.
Lamfalussy, who left his native Hungary after World War Two and became a Belgian citizen, was the first president of the European Monetary Institute, the predecessor of the European Central Bank.
He was replaced by Dutchman Wim Duisenberg in 1997, who would become the first president of the bank overseeing monetary policy for the euro zone.
Lamfalussy later oversaw the implementation of a new system designed to streamline EU regulation for the financial services industry, known as the Lamfalussy process.
One of its early results was the harmonising of regulation for investments services, known as the Markets in Financial Instruments Directive or MiFID.
Lamfalussy studied at Belgium's Catholic University of Leuven and Oxford University in Britain, and later taught at Louvain in Belgium and Yale University in the United States.
He held various jobs at the Bank for International Settlements in Basel before becoming its director until the end of 1993. His presidency of the European Monetary Institute lasted from 1994 until 1997.