Papua New Guinea's Minister of Intergovernment Relations says there are concerns about emerging power struggles between ex-combatant groups on Bougainville for leadership of the island.
Sir Peter Barter says ex-combatants are already vying for leadership positions once the peace monitoring groups leaves on June 30.
Sir Peter says the departure of the peace monitors and the absence of a local administration will create a power vacuum which will test Bougainville's stability.
But he says the Bougainville Constitutional Committe and PNG government are working on plans to maintain order on the island during its transitional stage.
"You have a bit of a vaccum which leaves law enforcement in the hands of the PNG police contingent based in the main centres. The Constitutional Committee is sitting down with the police and leaders in Bougainville to try to work out a way we can make the auxiliary police and ex-combatants work together."
Sir Peter Barter says so far around 93 percent of weapons registered with Peace Monitors have been handed in as part of the weapons disposal programme.
He also says that UN Observer team will begin assessing the level of security on Bougainville before deciding whether or not to approve the progess of the programme.