Maersk Shipping says the dispute between the Port of Auckland and the Maritime Union is harming New Zealand's reputation as an exporter.
Maersk New Zealand managing director Julian Bevis says there is growing frustration amongst the port's customers over the continued strikes and he warns the two parties to resolve it as quickly as possible.
The Maritime Union on Thursday issued another strike notice, effectively doubling a planned seven day strike starting on 24 February.
Mr Bevis says Maersk will have to divert more vessels to other ports if the strike goes ahead, and he says the ongoing dispute is a bad look for this country's export led recovery.
He says export customers will increasingly be questioning New Zealand's ability to supply in a consistent and sustainable way.
Mr Bevis says a stable supply line is an essential part of this country's economic infrastructure and productive ports have to be part of that.
He says the management of the port is quite right to be pursuing increased productivity and how they go about that is up to them.
Mr Bevis says this needs to be resolved as soon as is practicable.