He died of pneumonia and related complications at a private hospital in Kota Kinabalu this morning, the New Straits Times reported.

A wake will be held at the Agut Jubili Lighthouse in Penampang, while the funeral mass is scheduled for 10am on Tuesday at the Church of Mary Immaculate.

A veteran civil servant, Sipaun eventually rose to the rank of state secretary, serving in the position from 1988 to 1993.

He was later appointed vice-chairman of the Human Rights Commission (Suhakam) from 2003 to 2010.

Sipaun was renowned for speaking out on issues related to democracy, governance and civil liberties. He also fought for the rights of the people of Sabah.