A spokesman for the state-owned railway company said that like any freight business, KiwiRail looks for ways to move freight as cost efficiently as possible.
"KiwiRail has been working with its customers using the Northland line and consolidated their requirements to one daily train. The change frees up operational resources to be used elsewhere."
He said KiwiRail had worked with its customers to consolidate their freight needs to one daily train, but was unable to provide figures on how much tonnage would be on the trains.
"However, essentially the volume of freight carried will remain unchanged. If new commercial volumes are there we will reinstate trains.
"We are already in discussions over new opportunities," the spokesman said.
"The line remains open between Auckland and Otiria and should freight volumes at a commercially acceptable return be made available, KiwiRail is committed to providing services."
Mr Peters said the decision to slash the service was a disgrace, being done under subterfuge and heads should roll on the KiwiRail board over it.
"The result will be a significant drop in tonnage and it comes just weeks after KiwiRail shut down the Otiria-Kauri line - or movements on the line - whilst ministers in Parliament keep saying the line is still open," he said.
"If KiwiRail is doing the Government's bidding and shutting services as forecast, effectively they're shutting down critical rail services to regional New Zealand.
"Meanwhile, multiple unit leviathans are heading down our highways causing enormous damage to roads and creating major safety issues.
"This is one further disgraceful KiwiRail decision and death by a thousand cuts for the provinces."
