Former Papua New Guinea Prime Minister Sir Rabbie Langanai Namaliu, 75, passed away from a sudden illness in Rabaul last Friday.
Sir Rabbie served as PNG's fourth prime minister from July 1988 to July 1992.
He had a long and distinguished political career serving in many important roles, including as foreign minister in the early days in government, and later as the speaker of parliament from 1994 to 1997.
He was also a pioneering student and graduate of the University of PNG and became a leading figure during PNG's post-independence era along with Sir Mekere Morauta, Sir Anthony Siaguru, and Sir Charles Lepani.
The group were often referred as the "Gang of Four" for their influence in shaping PNG politics.
Prime Minister James Marape said PNG had "lost a great statesman."
"He had a distinguished career in the public service, in academia, politics and business," Marape said.
"I join with family, friends, people of East New Britain and Papua New Guinea in mourning the passing of Sir Rabbie."
Marape has confirmed that the former leader will be accorded a state funeral to honour his contributions to the country.
Sir Rabbie's family members told local media that he had been unwell for a few days and passed away in the process of being medivaced to Port Moresby.
PNG journalist Scott Waide told ABC Pacific that Sir Namaliu was a "typical Melanesian leader".
"He drew on his cultural roots, was always consultative, and at a time when there was so much instability [in PNG] during the Bougainville crisis, he survived four years in government as prime minister and survived many votes of no confidence," Waide said.
"So he was that prime minister that embodied a typical Melanesian leader and very well respected across the Pacific as well as in ACP [African, Caribbean and Pacific] countries."