A ship with nuclear waste will be passing through the Tasman Sea bound for Japan.
Greenpeace says it could happen this weekend, but the New Zealand Minister for Disarmament won't confirm any date.
Marion Hobbs' office says the trip by the UK registered vessel, Pacific Sandpiper, is the tenth such shipment of its type.
It carries Japanese nuclear material, which was sent to France for re-processing, being returned in solid glass-like blocks for storage in Japan.
Greenpeace says the ship left France on February the 17th and will enter the Pacific via the Tasman Sea.
It's calling the cargo the most radioactive material ever produced.
Greenpeace says it's warned Pacific Island countries about the shipment.
Pacific Island countries have repeatedly called for a stop to such shipments, yet no country along the route appears to have been formally told about the Pacific Sandpiper.