Papua New Guinea's prime minister has indicated there's no guarantee the independence referendum in Bougainville will proceed as scheduled.
The vote is scheduled for June 2019.
It is the final stage of 2001's Peace Agreement between Port Moresby and Bougainville signed to mark the end of a bitter civil war.
Responding in parliament to questions about PNG's commitment to the referendum, Peter O'Neill said it was subject to fulfilment of all obligations in the Agreement.
These include the establishment of the rule of law, a proper government structure on Bougainville and disposal of illegal weapons.
Mr O'Neill said those obligations are yet to be met.
"It's a long way off so I don't want Papua New Guinea and Bougainvilleans to think it's an easy path, just that tomorrow we will wake up and we'll go and have a referendum. It may be such that it'll be not possible."
"So we need to work between now and then, to work harder in making sure that we attend to the issues that are clearly defined in the Peace Agreement."
Bougainville's president, John Momis, said the critical factor in the region's struggle since autonomy has been Port Moresby withholding funding that's guaranteed under the Peace Agreement and the constitution.
And Papua New Guinea minister of Bougainville Affairs, Father Simon Dumarinu, said Mr O'Neill has issued Bougainvilleans a challenge over the referendum.
Father Dumarinu, who is the MP for Central Bougainville, said the prime minister is challenging Bougainville to work to achieve these goals in time for the vote.
"For me, it's a challenge. It's a challenge to the Bougainvilleans, the government on the ground and the people together. It's a challenge to them from the prime minister in regards to this question."
Father Simon Dumarinu said both governments need to work together to meet the timeline.