Australia's refugee intake would increase to 50,000 a year, including 10,000 via a new "skilled refugee" category, under a policy to be announced by the Greens.

The policy would provide a "dignity package" for asylum seekers waiting for their claims to be processed in Indonesia and Malaysia to discourage them from attempting to come to Australia by boat.

It would also shut down the offshore detention centres on Manus Island and Nauru, saving an estimated $2.9 billion over four years, most of which would be re-invested into "a fairer system that helps more people".