The first wave of boat people sent to Nauru will face primitive living conditions and could have to sleep in tents and use bucket showers and drop toilets, a Defence Department document says.
Defence teams will begin building a detention centre on the remote Pacific island nation on Friday if Parliament passes laws this week to revive offshore asylum processing.
Julia Gillard expects the first group to be sent there within a month.
The Prime Minister met Defence Force chief David Hurley yesterday morning to map out plans to re-establish immigration detention centres on Nauru and the Papua New Guinean province of Manus Island.
The military's involvement comes despite Gen. Hurley warning in 2010 it was inappropriate to use defence resources to build detention camps because it would sap the ADF's ability to conduct operations in Afghanistan and run war games.
In a brief prepared for Opposition Leader Tony Abbott in the event he won the last election, the Defence Department said that nonetheless within one week it could set up a "very basic interim facility" on Nauru with tents, barbed-wire fences, drop pit toilets, bucket showers and limited power for 500 people.
Within four weeks, temporary huts would supplement tents and improved fencing, basic sewerage and a kitchen with electricity would be available.
The brief, which Gen. Hurley signed off, said it would cost $3 million a week to have three navy ships take asylum seekers to the camp.
Ms Gillard said asylum seekers sent to Nauru and Manus Island would face very basic amenities.
"As for the temporary facilities, yes they would involve tents and other temporary structures," she said.
Estimates on the cost of detaining people on Nauru vary.
The Houston panel said it would cost between $1.2 billion and $1.4 billion over four years to accommodate 1500 people on Nauru, the same number held there under the Howard government.
It said a camp on Manus Island for 600 people would cost $900 million over four years.
But in a report to the Government in January, immigration officials estimated it would cost $2 billion over four years to detain 750 people.
The report warned that holding 1500 people on Nauru could lead to tensions because of overcrowding.
After inspecting the two former camps on Nauru, the department said a lot of work would be needed to refurbish the buildings and it would take at least three months for one camp to be made habitable.
It warned there was a lack of fresh water and staff lodgings. One campsite had no permanent water supply, toilet blocks, working sewerage plant, shade or recreational facilities.
The officials said many of the surviving Howard-era buildings were in use, including by a school that moved in after its original home burnt down.
When the Pacific solution was in place between 2001 and 2008, 1637 boat people were processed on Nauru and Manus Island.
Of those, 705 were resettled in Australia, 401 in New Zealand and 47 in Sweden, Canada, Denmark or Norway. One person died and 483 returned home voluntarily.