Diversified giant Rio Tinto on Monday announced that it was “reviewing” its options over its 53.83% shareholding in embattled Bougainville Copper.

Bougainville’s Parliament last week passed a new Mining Act, which devolved power to regulate the mining industry from the government of Papua New Guinea to Bougainville’s autonomous government.

The new Mining Act resulted in Bougainville Copper’s mining licences being revoked and replaced with exploration licences. The exploration licences would allow Bougainville Copper to apply for a new mining lease, subject to the outcome of negotiations with the Bougainville Mineral Resource Forum.

“In light of recent developments in Papua New Guinea, including the new mining legislation passed earlier this month by the autonomous Bougainville government, Rio Tinto has decided now is an appropriate time to review all options for its 53.83% stake in Bougainville Copper,” the miner said on Monday.

Bougainville Copper has confirmed Rio’s decision, with chairperson Peter Taylor saying that the company’s remaining shareholders would be kept informed of any decisions.