The South Pacific islands will become the world's newest nation if the Papua New Guinea Parliament approves the referendum results. The vote was part of a peace process that ended a decade-long war.
The South Pacific islands of Bougainville overwhelmingly voted for independence from Papua New Guinea, according to official referendum results released Wednesday.
Read more: The quest for national sovereignty
The non-binding results, which require ratification from Papua New Guinea's parliament, could create the world's newest country.
Almost 98% of the 181,067 votes cast backed independence for the Melanesian island.
The referendum was part of a peace deal ending a 1988-1998 civil war between Bougainville and Papua New Guinea that left at least 15,000 people dead.
Although there are fears that an independent Bougainville could set a precedent for other independence movements in tribally diverse Papua New Guinea, the scale of the victory for the pro-independence movement will be difficult for Port Moresby to ignore.
Rejecting the results could reignite conflict and endanger the peace process.
The civil war was largely fought over disputes about revenue sharing from the now-shuttered Panguna copper mine, which once accounted for 40% of Papua New Guinea's exports.
The mine is estimated to still hold billions of dollars of copper and gold.
Independence is likely to set off a dash for influence among regional powers China, the US and Australia.
Bougainville is about 1,000 kilometers (600 miles) west of Port Moresby and its people are culturally distinct from Papuans.
From the 1880s up until World War I, Bougainville was part of German New Guinea. Following the war, Australia occupied the island and then in 1975 it became part of Papua New Guinea.
cw/stb (AFP, dpa, Reuters)