Francis Ona, believed to be in his 50s, the charismatic leader of a bloody secessionist movement in the Papua New Guinea province of Bougainville, died Sunday in Australia.
He may have died of malaria, Papua New Guinea's National Broadcasting Corp. reported.
After 16 years of seclusion, Ona emerged from his mountain retreat a few weeks before elections May 20 to proclaim Bougainville already independent from Papua New Guinea.
He had begun referring to himself as king of the province in the last few years.
His movement's opposition to rule from the Papua New Guinea capital, Port Moresby, left 15,000 dead during the 1988-98 conflict, most through disease and starvation. Fighters were disaffected with the government and with the huge Panguna copper mine, then operated by Australian mining giant CRA.
A cease-fire signed in 1998 ended the war, and in 2001, the island of 180,000 people about 560 miles northeast of Port Moresby was promised a referendum on independence in 10 to 15 years.