Approval has been given for radioactive uranium material to be shipped through New Zealand ports for the next five years as it makes its way from Australia to the United States.
The uranium ore concentrate, or yellowcake, is from a mine in the Northern Territory owned by Energy Resources Australia. When refined, it is used as fuel for nuclear power plants.
The mining company says it has been shipping yellowcake via Auckland regularly.
This year, two ships carrying the uranium will also stop in Nelson, Napier and Tauranga.
The Environmental Risk Management Authority has approved the trans-shipments, saying the risks are extremely low.
The yellowcake, which has low radioactivity but is toxic, remains on board and is sealed below decks in containers.
Energy Resources Australia says it has been shipping the product for 30 years without incident.