They voted in highland villages and on remote atolls. Even 15 youths who live in the jungle and wear bright Upe hats as they undergo traditional training to become men had the chance to vote.

Regular voting ends on Tuesday while any remaining postal votes will be accepted through to Saturday. The results will be announced in mid-December.

The referendum is nonbinding, and a vote for independence would then need to be negotiated by leaders from both Bougainville and Papua New Guinea. The final say would then go to lawmakers in the PNG Parliament.

Chief Referendum Officer Mauricio Claudio said there had been long queues and high enthusiasm at many of the 828 polling places.

"During polling we've witnessed a festive and joyous mood," he said. "There have been dancing troupes and whole communities getting together."

Claudio said that giving Upes a chance to vote at male-only polling stations was one of many referendum firsts. He said election officers hiked for two hours into the jungle to collect the votes.

The young Upe men can remain isolated from their communities for several years as they learn about culture, medicine, hunting and other skills. During this time, they wear the tall, woven Upe hats that hide their hair and are forbidden to be seen by women.

Election officers also travelled by overnight boat to get to some of the five offshore atolls and visited a police lock-up to collect votes from prisoners.

Claudio said there was only one disruption, in the Konnou area, where a long-simmering dispute led police to advise referendum officers to close one polling station. The affected voters got a chance to cast their ballots elsewhere.

Complicating the voting process were the limited communications throughout the region and the traditional way many people live, including not owning any photo identification. Added to that, the Bougainville Referendum Commission only secured its funding in March.

But more than 40 UN staffers and over 100 international observers helped oversee a process that Claudio said had gone remarkably well.

The referendum is a key part of a 2001 peace agreement that ended a brutal civil war in which at least 15,000 people died in the cluster of islands to the east of the PNG mainland.

The violence in Bougainville began in the late 1980s, triggered by conflict over an enormous opencast copper mine at Panguna. The mine was a huge export earner for PNG, but many in Bougainville felt they got no benefit and resented the pollution and disruption to their traditional way of living.

The mine has remained shut since the conflict. Some believe it could provide a future revenue source for Bougainville should it become independent.

Experts believe the 250,000 to 300,000 people of Bougainville will vote overwhelming in favour of independence ahead of the other option, which is greater autonomy.

But the process of becoming a separate nation could take years to achieve.

Australian Associated Press