Hong Kong's leader said on Tuesday he strongly opposed Japan's release into the sea of treated radioactive water from the crippled Fukushima nuclear plant and the city would "immediately activate" import controls on Japanese seafood.
On Thursday, Japan will begin releasing more than a million tons of water from the plant north of Tokyo, insisting it is safe to do so. The plant was wrecked in a 2011 tsunami and the water has mostly been used to cool damaged reactors.
The government of the Asian financial hub said Hong Kong's ban would take effect from Aug. 24, the day Japan starts its release.
Though approved by the UN nuclear watchdog, the plan to dump the water has faced opposition at home and abroad, including from China, over worries about food safety.
Hong Kong Chief Executive John Lee said the release was "irresponsible" and posed "impossible risks to food safety and the irreparable pollution and destruction of the marine environment."
Lee, in a post on his Facebook account, said he had told Environment Secretary Tse Chin-wan and relevant departments to immediately activate import controls to protect food safety and public health.
"There is no timetable at this point about how long the ban will last," Tse told a press conference, adding that a decision would depend on data and information from the Japan after the discharge.
In July, Hong Kong said the ban would cover imported aquatic products from the Japanese regions of Tokyo, Fukushima, Chiba, Tochigi, Ibaraki, Gunma, Miyagi, Niigata, Nagano and Saitama.
But exports from 13 other regions would still be allowed, it added.
The measure covers live, frozen, refrigerated, dried aquatic products, sea salt and seaweed.
Hong Kong is Japan's second largest market, after mainland China, for agricultural and fisheries exports.
Japanese restaurants are popular in the special administrative region of China and Japan is a favourite holiday destination for many residents.
Many of the restaurants are grappling with the looming ban, with some planning to add more meat to their menus as they anticipate losses of up to 40%.