Businessman and philanthropist Martijn van der Vorm, who invested millions of euros in projects in Rotterdam, has died at the age of 67.

Investment firm HAL, where Van der Vorm spent 21 years as chairman before becoming chair of the supervisory board last year, announced his death on its website. The cause was not disclosed.

“With his enterprising and creative spirit, leadership and eye for detail, but also for the person behind the numbers, he made a long and remarkable contribution to the success of HAL, our company and all his colleagues,” the company said.

Van der Vorm lived a reclusive life in Monaco, rarely giving interviews or having his photograph taken. His family fortune, valued at €9.4 billion, was made from the Holland-America Line, which was sold in 1989.

The proceeds were used to found HAL, which is a major shareholder in companies including offshore energy firm Boskalis and online retailer Coolblue.

The Van der Vorm family also underwrote projects in Rotterdam including a fund to lift 1,000 families out of poverty and cultural projects such as the depot of Museum Boijmans van Beuningen and the newly reopened Nederlands Fotomuseum.

But its commitment to the public good was called into question when NRC published details of the elaborate financial constructions it used to avoid paying tax.

An investigation by the newspaper found that the family struck a secret deal with the finance ministry in the 1950s that allowed it to save six million guilders by donating part of an inheritance to its own charitable foundation.

Rotterdam’s mayor, Carola Schouten, said Martijn van der Vorm’s value to the city was “incalculable” and the council was deeply saddened to learn of his death.

“Many of the things he did for the city and its residents took place out of the spotlight,” she said. “His ideas and his approach have made a lasting impression on the city that was so close to his heart.”