Australia on Tuesday announced a A$500 million ($340 million) climate change package for Pacific island countries, which have been increasingly vocal in demanding their powerful neighbor curb its carbon emissions.

Prime Minister Scott Morrison said the funding, drawn from Australia's existing international aid budget, would help Pacific island nations invest in renewable energy and climate change resilience.

The climate-sceptic leader made the announcement before traveling to the Pacific Islands Forum in Tuvalu, where island nations threatened by rising seas have vowed to put global warming at the top of the agenda.

Smaller members of the 18-nation grouping have been sharply critical of Australia's climate policies ahead of this year's summit amid a diplomatic push from Canberra to counter China's growing power in the region.

High-level representatives have criticized Australia for not doing enough, with Fiji's Frank Bainimarama saying Canberra's reliance on coal poses an "existential threat" to low-lying islands. 

There has also been disquiet in the Pacific that Australia recently approved the giant Adani coal mine in Queensland state.