Japan has begun its controversial discharge of treated waste water from the Fukushima nuclear plant into the Pacific Ocean, sparking protests in the region and retaliation from Beijing.
China is the biggest buyer of seafood from Japan, and on Thursday it said it would block all such imports.
Japan says the water is safe, and many scientists agree. The UN’s nuclear watchdog has also approved the plan.
But critics say more studies need to be done and the release should be halted.
More than a million tonnes of water stored at the nuclear plant will be discharged over the next 30 years.
China, which has been the most vocal of opponents since the plan was announced two years ago, called the water discharge an “extremely selfish and irresponsible act” and said Japan was “passing an open wound onto the future generations of humanity”.
Shortly afterwards, China’s customs office announced that an existing ban on seafood imports from Fukushima and some prefectures would be immediately extended to cover the whole of Japan to “protect the health of Chinese consumers”.
The move is calculated to inflict economic damage, and Japan has admitted that businesses will take a “significant” hit. Mainland China and Hong Kong together import more than $1.1bn (£866m) of seafood from Japan every year – making up nearly half of Japan’s seafood exports.
But analysts say that the reactions from China in particular, are as much motivated by politics as they are by genuine concerns.
Tokyo’s relationship to Beijing has deteriorated in recent years as it draws closer to the US and also shows support to Taiwan, a self-ruled island claimed by China.
