China on Thursday banned all Japanese seafood imports over what it said was the "selfish" release of wastewater from the crippled Fukushima nuclear plant.

Japan began discharging treated contaminated water from the stricken plant into the Pacific Ocean on Thursday in an operation it insists is safe but which has generated a fierce backlash from China.

Beijing's foreign ministry branded the release as an "extremely selfish and irresponsible act", saying in a statement that the move would "push the risks onto the whole world (and) pass on the pain to future generations of human beings".

Meanwhile, China's customs authority said it would "suspend the import of aquatic products originating in Japan from August 24, 2023, including edible aquatic animals".

The decision was taken to "comprehensively prevent the food safety risks of radioactive contamination caused by the discharge of nuclear wastewater from Fukushima into the sea", the General Administration of Customs said.

It would also "protect the health of Chinese consumers and ensure the safety of imported food", the authority added.

Access24 reports that Beijing had already suspended all food imports from 10 out of 47 Japanese prefectures in July, with Hong Kong following suit.

China imported over $500 million worth of seafood from Japan last year, according to customs data.

In 2011, three reactors at the Fukushima-Daiichi facility in northeastern Japan went into meltdown following a massive earthquake and tsunami that killed around 18,000 people.