UPDATED 12.51pm: Firefighters have blacklisted Auckland's lead fire truck over safety fears.

It's the first time in two decades they've taken such a move.

The New Zealand Professional Firefighters' Union has blacklisted Auckland City's main fire truck - the one that carries the "jaws of life" rescue equipment.

This means it can't be used in the event of an emergency.

Northern branch secretary Boyd Raines said it's only a matter of time before a truck fails on a job and somebody gets killed - whether it's a firefighter, or a member of the public.

"You can't A put the fire out or B do search and rescue if there's persons trapped in the fire."

The Union says there have been 215 faults in the more than a dozen engines operating across the country, since they were introduced 18 months ago.

"Members who are using them have lost their trust and confidence in the appliance itself, because of the constant failures of the trucks in one form or another."

Mr Raines said the faults could threaten lives.

He said the trucks have failed to pump water, door handles have fallen off and gears have stuck.

"When a truck fails to start when it's called to a fire that's pretty serious. It's not the first time. This truck and other trucks of the same make have failed in this way."

But the Assistant National Commander of the New Zealand Fire Service, Kerry Gregory doesn't share those concerns.

"I've got no concerns for the safety of the public or our firefighters - if I did I'd be taking them off.

"I would have no hesitation in removing any appliance myself, if I felt there was a genuine safety concern."

Labour's acting Internal Affairs spokesperson Clare Curran said firefighters wouldn't have taken this action if they weren't concerned about their own, and the public's, safety.

"Ultimately if public safety is at risk then the Minster responsible has to ensure that it's being sorted out. If there needs to be some sort of investigation then it should happen."

Internal Affairs Minister Peter Dunne, who's responsible for our National Fire Service, isn't prepared to comment on claims more than a dozen new fire engines are faulty.

Mr Dunne said he hasn't been briefed on the matter, and is referring all enquiries to the National Commander of the Fire Service.