Key Points:

Rimutaka Prison was again plunged into chaos today as inmates took control of a section of a youth offenders unit, causing the lockdown of the entire prison.

The incident began this morning in the youth unit, understood to hold up to 40 teenaged inmates, and Department of Corrections general manager operations Bryan McMurray said staff were forced to take control of one section.

During the incident at the prison north of Wellington, understood to involve about 15 inmates, several made their way on to the roof of a building and had to be talked down, ending the longer than five-hour incident.

Mr McMurray said the prisoners damaged buildings and police were called in give back-up to Corrections staff.

"Our first priority was to maintain public safety by securing the prisoners and preventing further damage to buildings.

"We have achieved this, all the prisoners are now secured and charges will be considered for all the offenders in this incident."

He said no staff were injured and because the offenders were confined to the unit, there was no risk to the public.

Mr McMurray described such incidents as a "reality" for prisons worldwide.

The incident would be fully investigated.

Rimutaka Prison has been plagued by problems this year, and rival Black Power and Mongrel Mob-aligned youths rioted in April causing thousands of dollars worth of damage.

In March, 11 staff were stood down pending investigations into corruption and smuggling.

The same month Corrections Department regional manager Dave East was put on special leave facing claims of mismanagement at Rimutaka.

It was also revealed convicted rapist Peter Mana McNamara, 37, managed to father a son while serving seven years in the prison.

Four guard were also suspended following allegations a convicted rapist was allowed conjugal visits while receiving medical care at Wellington Hospital.

This month the Employment Relations Authority ordered the prison to reinstate a prison officer who allegedly assaulted an inmate, finding there was insufficient evidence to fire the guard.