Closing offshore detention saves $2.9 billion, budget office says

Closing down offshore immigration detention centres and moving asylum seekers to the mainland for processing in the community would save the federal government coffers $2.9 billion.

The Parliamentary Budget Office has crunched the numbers on an Australian Greens election policy to shut down the centres on Nauru and Papua New Guinea's Manus Island.

It calculated $2.9 billion would be saved over four years from 2015-16 onwards if offshore asylum seekers are sent to the mainland.