The 74-year-old's body was found on Monday night on railway tracks at Blaubeuren in south-western Germany.

Mr Merckle's holding company, VEM Vermoegensverwaltung, had been in talks with banks to secure credit after its business interests ran up high levels of debt, and also lost value amid the global financial crisis.

The company declined to say how much it needed, or to comment on German media reports it might have to sell some of its interests.

In addition, the holding company said it had suffered heavy losses on shares of car maker Volkswagen AG, which fluctuated wildly last year as fellow car maker Porsche SE moved to increase its stake in the company.

A family statement said, ''Adolf Merckle lived and worked for his family and his firms. The distress to his firms caused by the financial crisis and the related uncertainties of recent weeks, along with the helplessness of no longer being able to act, broke the passionate family businessman, and he ended his life.''

Mr Merckle helped turn his grandfather's chemical wholesale company into one of Germany's biggest pharmaceutical wholesalers, Phoenix Pharmahandel, in which he held a 57 per cent stake. He used his wealth, estimated last year to be $US9.2billion ($A12.8billion), to take stakes in HeidelbergCement and Ratiopharm. HeidelbergCement shares were down 5.8 per cent at 31.39 euros in Frankfurt trading after news broke of his death.

Mr Merckle also owned stakes in companies that made a wide range of goods, from all-terrain vehicles to software and textiles.

The Governor of his home state of Baden-Wuerttemberg, Guenther Oettinger, said the region had lost a ''great entrepreneurial personality'' who built up a ''business of European significance''.

Mr Merckle was awarded Germany's highest decoration, the Bundesverdienstkreuz, in 2005, but despite his wealth and prominence in corporate Germany, he mostly avoided publicity.

He is survived by his wife, Ruth, and four children.

In other apparent suicide cases linked to the financial crisis, New York-based money manager Thierry Magon de la Villehuchet, 65, who may have lost client funds invested with Bernard Madoff, is presumed by police to have killed himself in his Madison Avenue office last month; and Kirk Stephenson, who helped start Luqman Arnold's investment company Olivant, was judged by a British coroner's court to have committed suicide. AP