Several Corrections staff including three managers have been suspended from work as part of a lengthy corruption investigation at Rimutaka prison.

Five staff members were on Thursday placed on special leave following allegations of staff misconduct, Corrections chief custodial officer Neil Beales said in a statement.

It is understood three are managers.

The Upper Hutt prison is the subject of a long-running police investigation into what the Department of Corrections dubs "integrity concerns".

Allegations against staff include smuggling contraband, inappropriately accessing prisoner information and failing to maintain professional boundaries.

Beales said since November 2020 police have been "referring instalments of information obtained during their inquiries" to the counter-corruption Integrity Assurance Team within Corrections.

"The information relates to alleged workplace misconduct that may breach our code of conduct," Beales said.

"As we've said previously, we welcome the inquiries being undertaken by Police at Rimutaka Prison since July 2020, and staff are continuing to assist Police with these inquiries."

"Our inquiries identified 10 staff whose alleged actions were of concern and we have decided they should be investigated further."

Of the 10 staff, one has resigned.

Two were already on gardening leave. Five additional staff have been placed on "special leave", Beales said.

The final four staff will be spoken to by senior management shortly, Beales said shortly before noon Thursday.

He confirmed the staff included members of the management team and "varying levels" of Corrections officers.

"We are investigating a range of allegations of staff misconduct.

"This includes introducing contraband [including food and cellphones], workplace bullying, failure to follow procedures critical to the safety and security of the prison, failure to maintain professional boundaries and inappropriately accessing prisoner information."

None of the allegations relate to sexual misconduct, Beales said.

"We will not tolerate this type of behaviour in our prisons. We expect a high standard of conduct from all employees. The nature of our work means we must act beyond reproach at all times."

Detectives from the police National Organised Crime Group are continuing to run their investigation.

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