ASYLUM seekers would get almost $500 a fortnight on full welfare and access to other benefits under a Greens immigration policy that would fast-track processing and also give them full work rights.

Greens Leader Christine Milne will today unveil the plan to treat asylum seekers more humanely and lift the payment rate from the current $442 - calculated at 89 per cent of the $497 fortnightly Centrelink Newstart payment - to the full level of the benefit.

They would have rights to full welfare including rent assistance as well as full work rights to allow them to compete with Australian workers for jobs.

While Labor and the Coalition are locked in an arms race with increasingly hard line policies, the Greens would abolish offshore processing and asylum seekers would be processed through onshore detention, health and security checks within 30 days before being released into the community on bridging visas instead of current lengthy waits.

The minor party will argue the full welfare rights will get asylum seekers contributing to the economy and the extra payments are affordable under its Safer Pathways plan that saves $3.2 billion over the forward estimates by dismantling costly offshore processing, having less people in detention, closing offshore detention centres and closing and not building new onshore facilities.

The humanitarian intake would also be increased from the current 20,000 people to 30,000 people a year.

But the plan is likely to come under fire from the government and opposition for reverting to onshore policy and providing extra incentives for people to board dangerous boats and risk their lives travelling to Australia.

Asked about the safety of reverting to onshore processing given the hundreds of drownings from boat capsizings, Senator Milne yesterday said the offshore processing regime since the Houston report last August had been a failure - shown by ongoing boat arrivals in record numbers.

Senator Milne said it was important to cut both the financial and social costs while treating refugees in a more humane way and not end up with a generation of "damaged people".

"We believe deterrence does not work and that has been demonstrated in the past 12 months," she said.

"There are huge social and financial costs by creating an underclass of people who cannot work and who are destined for poverty. Why wouldn't you give them that support and allow them to contribute their skills to the Australian community?"

The full immigration policy can be revealed by News Corp Australia after the party launched its campaign in Canberra yesterday, demanding a Senate inquiry to scrutinise the legal, financial and moral implications of the current regime.

The asylum seeker policy was costed by the Parliamentary Budget Office but it did warn the figures had a "low reliability" because of the difficulty in estimating the costs of the Nauru centre and savings from shutting down some onshore facilities.

Julian Burnside will launch the policy today with Greens immigration spokeswoman Sarah Hanson-Young in Adelaide.

Senator Hanson-Young said economic savings were just one of the many advantages of the party's refugee policy.

"Australia's international reputation is being tarnished by the old parties and their obsession with cruelty," she said.

"While the Labor Party wants to lock children up on Nauru and Tony Abbott wants to set fire to boats in Indonesia, the Greens are offering a considered, evidence based approach."

Watch Greens Leader Christine Milne on Meet The Press today on Channel Ten.

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