German billionaire Heinz Hermann Thiele, the biggest shareholder in Lufthansa airline, died Tuesday aged 79, announced Knorr-Bremse, the company through which he built his fortune.

Thiele, a rail industry tycoon and one of Germany's richest men, died "surrounded by his family in Munich", Knorr-Bremse said in a statement.

Derided as a "caveman capitalist" by trade unions and dubbed a "patriarch" by others, Thiele had become Lufthansa's largest shareholder last year with a 15.5 percent stake.

He battled with Germany's government last June, making no secret of his scepticism about plans for the state to take a 20 percent stake in Lufthansa in exchange for a huge rescue package to keep it afloat during the pandemic.

But on the eve of the crucial vote, managers at Lufthansa heaved a sigh of relief as Thiele said he would back the bailout to avoid insolvency.

Married with two children, Thiele trained as a lawyer and started out in 1969 in the patents office at brakes manufacturer Knorr-Bremse.

In the 1980s he saved the company from bankruptcy in a loan-backed buyout, transforming it into a market leader for rail and heavy truck brakes.

Factory staff worked for 42 hours per week rather than the 35 typical elsewhere in the sector, forging the core of Thiele's wealth.

Last year, Forbes magazine estimated his net worth at around 15 billion euros ($18.2 billion).

Beyond the business world, Thiele also attracted headlines with controversial remarks on politics and international relations.

He once told Manager magazine that Russian President Vladimir Putin "may not be an exemplary democrat but is a very competent politician".