The head of Christchurch Men's Prison and two senior staff are on special leave as the Department of Corrections begins an investigation into security procedures at the prison.
The department's southern region commissioner, Ben Clark, said he has recently become aware of potential non-compliance with security procedures.
He has ordered a review and appointed another manager as head of the prison while this was carried out.
Mr Clark said although there was no suggestion the prison's security had been compromised, it was extremely important that all aspects of security procedures were complied with.
Corrections declined to comment further.
Christchurch Men's Prison houses just over 900 inmates and is one of the country's largest jails.