The proposed Carmichael mine in central Queensland would become the country's largest mine, and is supported by both the Queensland and Australian governments.
But there is opposition from indigenous and environmental groups, who say it would have devastating environmental consequences, including for the fragile Great Barrier Reef.
The co-ordinator of the Pacific Islands Climate Action Network, Krishneil Narayan, said his organisation was joining the opposition because it would affect the Pacific, too.
