Documents leaked to The Guardian have uncovered an ambitious push to drive refugees and asylum seekers out of the facility, including forced separation and phasing out cooked meals.

But most of the plans either never came to fruition or largely collapsed, leaving the Turnbull government scrambling to reduce the centre's population ahead of an October 31 closure deadline.

In the 12 months to 31 March, 76 people left Australia's regional processing centre - either to live in transit accommodation, accept resettlement in PNG or return to their country of origin.

But government papers show 829 asylum seekers remain at the facility, with refugees awaiting potential settlement offers from the US and resisting inducements to live permanently in PNG.

A briefing paper by contractor Broadspectrum shows authorities last year planned to separate refugees from non-refugees and subject both cohorts to harsher conditions, including replacing catering with a cash supermarket.

The harshest treatment was to be deliberately meted out to non-refugees, who were to be housed in the western side of the centre, which lacks air-conditioning to temper the tropical heat.

One of the goals was to sever communication between the two groups and remove the "potential negative influences" of those friendships.

But refugees and advocates told Fairfax Media on Tuesday that despite attempts, the forced separation had largely broken down over the past year.

"It's not strict anymore. They tried to make it strict but it's not strict," said Ian Rintoul of the Refugee Action Coalition. "It broke down because of capacity more than anything else. They stopped trying to enforce it so much."

Meal catering continues for all asylum seekers, while a proposal to ban smoking at the centre did not proceed, and cigarettes are still sold there.

The 2016 Broadspectrum plan stated that "conditions and entitlements should become more attractive as asylum seekers move through the process", with extra incentives given to those who agree to resettlement in PNG.

Refugees on Manus Island have largely resisted that option, due to concerns about safety, healthcare and cost of living. Immigration Minister Peter Dutton last month said about 36 people had taken up the offer.

Iranian refugee and journalist Behrouz Boochani told Fairfax Media: "They used a lot of tricks to put people in a situation to accept the PNG option but only [a] few people accepted that."

On Monday, asylum seekers were told the centre would commence closure later this month, starting with M Block in the Foxtrot compound.

Mr Dutton used the announcement to reiterate that those who were not refugees needed to voluntarily leave PNG and go home.

"Now, as they can see, the government is definite about the closure date," he told Sky News. "If they are not refugees, they need now to make plans to return back to their country of origin.

"We'll help them do that ??? but it needs to be made very clear to them yet again that they aren't going to be settling in our country."

Some non-refugees have been forcibly deported, but the matter is complicated because some governments, including Iran, will not accept involuntary returns.

A spokesman for Mr Dutton said questions about operations at the facility should be directed to PNG authorities.

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