A massive shipment of plutonium mixed oxide (MOX) is meant to travel through the Cape of Good Hope on Saturday, Greenpeace Africa said in a statement.

"MOX shipments are simply not worth the risk, they are a major terror target and pose an enormous threat to the environment of all countries en route," said Rianne Teule, nuclear campaigner for Greenpeace International in a statement on Saturday.

The ships, Pacific Pintail and the Pacific Heron, were heavily armed and protected by specially trained British forces, the statement read.

They are to enter South African waters as they make their way from France to Japan.

The shipment left Chebourg port with about 1.8 tonnes of MOX fuel — enough to make 225 nuclear weapons — and will travel via the Cape of Good Hope.

"This MOX transport poses immediate contamination and security risks, and is yet another example of the dangers of nuclear energy... not only is the shipment unnecessary and insecure, there is no evidence that the containers carrying the fuel are safe from accidents," Teule said.

MOX fuel is an alternative nuclear fuel made up of a mixture of uranium and plutonium.

"This shipment is a reminder to the South African government that the health and environment risks associated with nuclear power are real, and that taking the nuclear route in power generation is not the solution to reducing climate change emissions.

"Nuclear power will provide too little, too late to address climate change and it is a dangerous distraction, sucking billions of rands in funding, away from the real solutions which could already be implemented today," said Brad Smith, programme director for Greenpeace Africa.

In a bid to stop this shipment, Greenpeace Africa has sent a warning letter to several African environmental ministers including South Africa's environmental affairs and tourism Minister, Marthinus Van Schalkwyk, urging them to take immediate action against the two ships.

Sapa