Wim Duisenberg, the former European Central Bank chief who helped create the euro currency, was found dead in his swimming pool in south-eastern France.
A post-mortem examination showed the 70 year old had drowned yesterday after an unspecified heart problem, a regional prosecutor said.
Police said he was found unconscious in the swimming pool at his home in the town of Faucon and could not be resuscitated.
Duisenberg "died a natural death, due to drowning, after a cardiac problem", said Jean-Francois Sanpieri, a state prosecutor in the nearby town of Carpentras.
Duisenberg was the first head of the ECB, serving from 1998 to 2003. Having shepherded the euro through its introduction in 1999, he became known as the father of the 12-nation European common currency.
"With his calm manner, he established people's basic trust in the euro," said German finance minister Hans Eichel. "We will remember his personality and what he achieved."
Tall with a big mane of white hair, Duisenberg sometimes came off as more of a professor than a heavyweight policy-maker. A chain-smoking golf lover, he kept a decidedly low profile as the ECB chief but was a major figurehead bearing overall responsibility for price stability in the euro zone of more than 300 million people.
During his tenure at the bank, Duisenberg was known for his cautious monetary policy and was eager to defend the euro through its early years. He sometimes frustrated financial markets and politicians by sticking to the bank's inflation-fighting stance, keeping rates higher than some investors and officials would have liked.
Duisenberg repeatedly said it was up to European governments to pursue structural reforms - such as loosening rigid rules on hiring and firing - if they wanted more growth.
Higher rates are the bank's main tool to fight inflation, but they can crimp economic growth. The bank's tight policy helped keep the euro a strong, stable currency even as it is criticised as a drag on growth.
Duisenberg, who unabashedly sought to model the ECB on the US Federal Reserve Bank, was at times referred to as "Europe's Greenspan" - a reference to Fed chief Alan Greenspan.
His selection as ECB chief was championed by Germany - Europe's biggest economy - but faced controversy when France proposed its central banker, Jean-Claude Trichet, as a rival candidate.
Mr Trichet, a friend of Duisenberg, took over in 2003. Mr Trichet, in a statement, called Duisenberg's death a "terrible loss," and credited him with a decisive role in setting up EU monetary institutions, overseeing the euro launch and building confidence in the currency.