He was arrested by the National Fraud and Anti-Corruption Directorate of the Royal Papua New Guinea Constabulary on Monday.
Brown is also a non-executive director of Australian Securities Exchange-listed wealth management company, ClearView, which alerted the ASX to the news.
"ClearView will provide updates on the matter when practicable," the company said.
NASFUND is an organisation which has $1.75 billion under management.
Brown is also a director of the PNG Institute of directors, and is a former head of private markets for Victorian Funds Management Corporation and a former portfolio manager with QIC.
He is also a former chairman of the Australian Private Equity and Venture Capital Association. Brown is a member of ClearView's board risk and compliance committee.
Brown has an MSc from Stirling University in Scotland, a BComm from the University of Auckland, he is a member of the CFA Institute, a member of the Australian Institute of Company Directors and a Council member of the PNG Institute of Directors
ClearView provides insurance, superannuation services and financial advice.