A shortage of prison officers means Corrections is being forced to transfer inmates to other jails to cope.
Meanwhile it's alleged some prisoners are being denied their basic human rights, including time out their cells, because of the lack of staff.
Corrections says it doesn't have a bed shortage.
Yesterday there were 9,061 inmates across the country's 18 jails, that have a combined capacity of 11,000 beds.
But at Christchurch Men's Prison there are insufficient prison officers to safely manage the muster and Corrections says it had to transfer a number of inmates to Otago and will send more there this week.
The Christchurch men's prison is short 44 fulltime frontline staff, which can include nurses, case mangers and corrections officers.