Two environmental activists have jumped into the sea beside armed cargo vessels carrying nuclear waste to Britain from Japan.

The vessels were passing through a protest flotilla of small yachts in the Tasman Sea between Australia and New Zealand when the Greenpeace activists attempted to slow them down.

An Australian politician jumped in the sea

The protesters who jumped into the water included Ian Cohen, an elected member of the New South Wales parliament in Australia.

British Nuclear Fuels Plc (BNFL), the owners of the waste, said the act was "lunacy".

Greenpeace claims the ships are carrying enough plutonium waste to make 50 nuclear bombs, which make them a potential target for terrorists.

The radioactive material is being returned to Britain because accompanying documentation had been falsified.

More than 50 protesters took part in the Nuclear-Free Seas Flotilla.

It consisted of yachts from New Zealand, Australia and the tiny Pacific islands of Vanuatu.

They battled high seas and unpredictable weather over the past two days to be ready to confront the two freighters, which left Japan on 4 July, in a stretch of water between Norfolk Island and Lord Howe Island.

Greenpeace says the protest was largely a symbolic one, and that it never expected the ships to stop.

A smaller flotilla took part in a protest last year when a nuclear shipment from France passed through the Tasman Sea en route to Japan.

Pacific island nations have opposed the shipment of nuclear materials through their waters.