It may be too hot to be Siberia, but prisoners in the Northern Territory are being sent to a salt mine to work.
The low-security inmates have been sent to Karinga Lakes, about 250km from Alice Springs, under the Northern Territory's new Sentenced to a Job programme.
The joint venture project, run by Rum Jungle Resources, extracts potassium sulphate from the mineral-rich lakes, and has been included in a programme touted to businesses as a pool of reliable labour that can be of "significant benefit to [their] bottom lines".
The NT Government says the prisoners have been sent to the remote Karinga Lake project because the company has had difficulty attracting other workers. But the United Voice union claims the Government is using prisoners as "slave labour", paying them well below the going rate for other mine workers.
"We've had some miners in those different areas we represent coming forward, and they're a bit worried because of these large mining companies who actually quite happily use undercutting of labour and undercutting of wages to try and maximise their profits while driving down the different areas," union secretary Matthew Gardiner said.
"If anyone's working in this sector, regardless of where they come from or what they've done, they should be paid at market rate ... No one in the mining sector works on award rate."
Gardiner told ABC Radio the award rate applying to Karinga Lakes was about A$16 ($18.20) an hour, compared to a going rate of about A$35.
The conservative Country Liberal Government launched the programme in February in a bid to both reduce the cost of incarceration and tackle high rates of re-offending.
"The Territory has the highest recidivism rate in the country with almost 50 per cent of people released from the system returning to gaol within two years," Correctional Services Minister John Elferink said.
"We must address this and this programme is one way of doing that."
Federal prisons in the United States operate a work scheme that requires all medically fit inmates to work in areas such as food service, plumbing, and groundskeeping.
They work for US12c to US40c an hour, with deductions to offset incarceration costs and to pay off fines.
Under the NT scheme prisoners receive award wages, with 5 per cent given to the Victims' Assistance Fund and A$125 a week deducted for "board". A small amount is allowed for use within the prison, and the rest is held in a trust fund and handed to prisoners on their release.