Prison officers at Australia's largest jail have begun a 48-hour strike over demands for more staff and better pay.
Officers at the Clarence Correctional Centre, near Grafton in the NSW Northern Rivers region, walked off the job at 6am on Wednesday and won't return until 7am on Friday.
This will mean the 1000 prisoners, including a men's maximum security wing, will likely be confined to their cells for two days and nights.
The strike follows action taken earlier this month and Community and Public Sector Union branch assistant secretary Troy Wright says he's not surprised officers rejected an offer by the prison's private operator Serco on Tuesday.
"Serco attempted to halt the strike by offering prison officers a rise in base pay rates, but paid for it by cutting overtime rates," he said.
"Overtime is a key component of prison officer's current take home pay as Serco has difficulty recruiting and retaining staff because prison officers at the prison are the worst paid in the country."
Officers were forced to work overtime to meet minimum staffing requirements and keep pace with the rising cost of living, he said.
"Serco have had two years to sit down with their prison officers and negotiate a fair outcome all parties can live with yet instead they've stonewalled, intimidated and lied to their Prison Officers every step of the way," he said.
Serco managing director Michael Strickland says he is disappointed another offer has been rejected.
"Serco has put numerous offers on the table and have been fair and reasonable throughout negotiations," he told AAP.
"The current offer is an increase of around 15 per cent to the current base rate of pay, on top of the 8.5 per cent already paid last year.
"This is a more than reasonable pay increase."
