The Pacific Concerns Resource Centre, or PCRC, says it's strongly opposed to plans for France to ship nearly two tonnes of recycled nuclear fuel to Japan.
The French nuclear group Areva has confirmed that it will be shipping a blend of plutonium and reprocessed uranium, or mixed oxide, along one of three possible routes - via the Cape of Good Hope, Cape Horn or the Panama Canal.
Greenpeace says two ships from Britain's Pacific Nuclear Transport company, each with armed police on board, would this week take on board the fuel at the northern French port of Cherbourg.
The PCRC's Tupou Vere says the shipment poses a grave risk to the ocean environment that Pacific people rely on.
"We are calling on the British, French and the Japanese governments to stop the shipment. One other concern that we have is that to date, there has been no mechanism worked out on the liability and who should accept liability for any collateral damage done as a result of the shipment."