Papua New Guinea's Minister of Inter Government Affairs says progress on Bougainville's autonomous government is running ahead of schedule and work on the second draft of the province's constitution was on time.
PNG's media reports Sir Peter Barter saying the main priority now is completing the containment of surrendered weapons and securing the approval of the United Observer Mission on the island.
He says ex-combatants have a particular responsibility in this regard.
UN approval of the end of stage two of the weapons disposal programme is needed before the constitutional arrangements for Bougainville can come into effect.
Sir Peter also says the Bougainville Peace Monitoring Group will pull out at the end of June despite attempts by the PNG government to have it delay its departure.
Sir Peter says tight budgets and other deployments had forced the decision by Australia, New Zealand, Vanuatu and Fiji to withdraw from the island.