A freight train has derailed near Mauku, southwest of Auckland.
The accident happened early today on the Glenbrook Steel Mill access line, KiwiRail spokeswoman Kimberley Brady said.
Because the train derailed on a branch line, it wouldn't cause any delays to normal services, Ms Brady said.
There were no injuries, she said.
The cause of the accident was not yet known and KiwiRail was waiting on inspection feedback before they could start to remove the freight cars.
"We don't know how long it will take at this stage but we're in the process of investigating the derailment then they'll start clearing the site and then repair the track," Ms Brady said.