Auckland Prison at Paremoremo is the country's only maximum security jail.

A campaign of "organised violence" by gang member inmates against guards has led to dozens of staff at Auckland Prison calling in sick on Sunday.

The Corrections Department confirmed it was forced to bring in guards from other prisons because of "a higher than usual number of staff calling in sick this weekend".

Alan Whitley, president of prison staff union the Corrections Association, said at least 30 staff did not turn up to work at the Paremoremo prison on Sunday, following an assault on a guard on Saturday.

DAVID WHITE/STUFF Corrections says organised attacks against prison guards by gang members were "gutless and unprovoked".

Whitley said the union had not directed staff to call in sick - instead, it had threatened not to unlock the prison's maximum security blocks on Sunday morning if Corrections "didn't have a safety plan in place".

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"The plan they had yesterday wasn't good enough - it wasn't working."

Saturday's assault was at the fifth attack by an inmate against a guard at the prison in the past week.

"They were basically moving the prisoner and he lashed out without any warning and punched a staff member," Whitley said.

"The staff member needed to go to hospital to be checked and treated. I understand he's recovering well at home at the moment."

On Friday morning, a Corrections officer was also bashed in the face by a prisoner with gang affiliations.

The violence was predominantly happening in the prison's maximum security blocks, when guards took prisoners out of their cells for exercise or showering, Whitley said.

"Any assault on a staff member is serious, but these are particularly concerning because they're happening within a very short period of time. And they're coming out of nowhere. There's no build-up to them.

"There needs to be more controls on how we're moving prisoners around. We're not far away from transitioning into a new building but we're still taking the same volatile, dangerous prisoners into the new building."

Jeanette Burns, the Corrections Department's northern regional commissioner, said she personally visited Auckland Prison on Sunday and it was "largely operating as usual".

"Over the last fortnight there has been an increase in organised violence toward staff, orchestrated by gang members at the prison," Burns said.

The prisoners responsible for the assaults have been segregated, and Corrections is "working with police to ensure that they are held to account through criminal prosecution".

Auckland Prison, New Zealand's only maximum security facility, is more than 50 years old and does not provide an "optimal environment" for managing maximum security prisoners, Burns said.

A new $300 million replacement facility is due to open at the prison this year. Corrections had also invested heavily in keeping staff safe, including the introduction of stab-resistant body armor and the expanded use of pepper spray.

Burns said the assaults had typically involved punches to the head or upper body, resulting in bruising and abrasions. Welfare support was being provided to all staff, and managers were "regularly checking on wellbeing".

The staff at Auckland Prison do an exceptional and brave job and the assaults against them were "gutless and unprovoked," she said.