BERLIN (AFP) - Otto Beisheim, billionaire founder of retail giant Metro and one of Germany's richest people, died Monday aged 89, the firm said, reportedly taking his life due to an incurable illness.

"He was suffering from an incurable disease and departed this life due to the hopelessness of his health situation," said a statement from the Otto Beisheim group.

Mass circulation daily Bild said he committed suicide. Founder of Metro Group, which now comprises 2,200 retail outlets in 32 countries in Europe, Asia and Africa, Mr Beisheim amassed a fortune estimated by Forbes in its 2012 billionaires list at US$3.3 billion (S$4.08 billion).

According to Forbes, he was the 344th richest person in the world and the 22nd wealthiest person in Germany.

Mr Beisheim brought the concept of cash and carry wholesaling, where retailers pick up goods themselves and pay for them immediately, to Germany in the 1960s after witnessing its success in the United States.

He set up the first cash and carry shop in Muelheim an der Ruhr, in western Germany, in 1964 and almost instantly enjoyed a roaring trade.

He exported the concept first in Europe, then worldwide, establishing the "Cash and Carry," "Media Markt" and "Real" chains in countries from China to France.

"Otto Beisheim was a pioneer and a legend in the German and international retail world ... with innovation, courage and ambition, he founded one of the world's leading retail firms," Metro said in a statement.

Through his charitable foundation, he supported schools and set up sports clubs and play areas for children.

He was married for 50 years to his wife Inge, who died in 1999. The couple never had children.