JAPAN began releasing thousands of tons of nuclear-contaminated waste water from the Fukushima plant into the sea in its second phase of discharges today.

A similar quantity of treated water will be released over the next 17 days as in the first round — 7,788 tons, authorities said. The release of contaminated water could take up to 30 years in total.

The discharges have sparked anger from environmental organisations, fisherfolk and some foreign governments.

Japan’s Communist Party chairman Kazuo Shii has slammed the release as “absolutely unacceptable” and a breach of the government’s promise to obtain consent from Fukushima prefecture and consult affected parties including fishing communities. 

The Japanese Federation of Fishery Co-operative Associations confirmed it is opposed to the discharges, which have also been condemned by Greenpeace Japan.

They have seriously affected seafood exports, with China, the largest customer, banning imported seafood from Japanese waters because of health concerns.

“Even if the water contaminated by contact with debris from melted-down nuclear fuel is treated with [the advanced liquid processing system], radioactive tritium cannot be removed.

“Furthermore, the government admits that the water also contains radioactive substances other than tritium such as caesium and strontium,” Mr Shii told MPs.

The Communist Party has proposed measures to stop groundwater leaking into the abandoned nuclear plant, which was disabled by a tsunami in 2011. It wants ministers to look at alternative storage policies for the contaminated water.

Fukushima plant officials say tests prove the water is safe, and the International Atomic Energy Agency has also signed off on the plans.