"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.
