The Bougainville Government is furious at statements by Papua New Guinea's Prime Minister that he has transferred his government's shares from Rio Tinto to the province's landowners.
The shares are in Bougainville Copper Ltd which had run the long closed Panguna mine in PNG's autonomous region of Bougainville.
Peter O'Neill told parliament he had no intention of giving the shares to the Autonomous Bougainville Government.
The ABG had wanted the PNG Government shares to give it a controlling interest in the mine and access to the company's years of research data.
Bougainville's President John Momis said the future of Panguna was the most sensitive issue in Bougainville and claimed Mr O'Neill's move was an interference in the peace process and would not help the landowners.
Describing the rift with PNG over the shares as the most serious dispute ever between the two, Mr Momis said Mr O'Neill was behaving in a neo-colonialist way, treating people as if they don't really matter.
"We are legitimate stakeholders," he explained.
"The Bougainville Peace Agreement empowers the people of Bougainville and that is one of the main reasons why Bougainville has been given autonomous powers, and that is to solve its own problems.
President Momis is seeking an urgent meeting with the PNG Government.
He said the alternative was for the ABG to cancel the BCL exploration licence under the Bougainville Mining Act.
He said as this was the only major asset of the company, all BCL shares would be worthless.
This would include the 19.2 percent equity that the national government had retained in the company.