The director of Christchurch Men's Prison and two of his staff are on special leave as the Department of Corrections investigate "compliance with specific security procedures" at the facility.
The Herald understands that prison director John Roper was on his final employment warning before he went on leave.
Corrections would not comment on Roper or the other staff saying it was an employment matter.
Corrections Southern Region Commissioner Ben Clark announced the news to staff at the prison today.
"Recently I became aware of potential non-compliance with the Department's security procedures at Christchurch Men's Prison," he said.
"Although there is no suggestion that the prison's security has been compromised, it is extremely important that all aspects of our security procedures are complied with."
Clark said in response to the situation he had requested that Corrections director of intel and operations, Ray van Beynen undertake a review into "compliance with specific security procedures".
"The prison director and two other senior staff from the prison are on special leave," Clark confirmed.
Operations support manager Russell Watkins will act as prison director in the meanwhile.
"I will update you further when I am able to do so," said Clark.
A Corrections spokeswoman said no further comment could be given at this stage.