Bougainville's regional government is firmly rejecting the proposal from Papua New Guinea's national government of free association or confederation instead of granting the autonomous region full independence, which is its only wish.
The parties recently bunkered down in a Christchurch military camp for several days to discuss the next stage of manoeuvring to deliver on the overwhelming will of Bougainville's people from 2019 after nearly 98 per cent of a non-binding vote elected to go it alone and gain nationhood.
The PNG national government agreed in the talks to table the autonomous region's referendum results in the parliament for MPs and undertake a vote to grant Bougainville independence possibly as early as 2027.
PNG prime minister James Marape has long held fears for the economic sustainability of the impoverished island of 300,000 people, and that accepting its independence could embolden a number of provinces to secede.
But Marape remains non-committal on his government's position as it battles to find common ground that benefits the PNG.
"My duty as Prime Minister is not only to Bougainville, but to the whole of Papua New Guinea," Mr Marape said.
Bougainville runs a copper and gold-rich mine whose revenue had flown into the coffers of PNG economy at the expense of local communities of the region that also resulted in civil unrest for a number of years.
Bougainville Attorney-General Ezekiel Masatt said that a fourth round of discussions cannot progress constructively until PNG is open enough to willingly accept that any deal must favour the autonomous region's current position of self-determination.
Massat put forward in Christchurch what he called a "Melanesian Solution", asking for the autonomous region to be granted some form of sovereign powers, effective immediately.
Bougainville was once ruled as a German colony with the northern parts of New Guinea for 30 years before Australian naval forces were forced to occupy the island from the start of the First World War until PNG annexed the island ahead of their full independence from Canberra in 1975.
But former PNG chief secretary Isaac Lupari has called for caution on the pro-independence stance of Bougainville, telling the Papua New Guinea Post-Courier masthead that the country's national constitution does not allow for any part of the country to secede.
"The pathway for determining Bougainville's future is enshrined in our national constitution," he said, "which makes it clear that the decision-making authority in relation to the 2019 Bougainville referendum results rests with the national parliament move to independence."
