Hong Kong will impose import curbs on seafood to seaweed from parts of Japan in response to a contentious plan to start releasing treated wastewater from the wrecked Fukushima nuclear plant into the Pacific Ocean. 

Chief Executive John Lee said Tuesday he had “immediately instructed” officials to initiate import control measures to “protect Hong Kong’s food safety and public health.” The move threatens to impact a broad swath of products that contribute to an industry worth hundreds of millions of dollars in seafood exports to the Asian financial hub.

Japanese Prime Minister Fumio Kishida earlier confirmed that the discharge of about 1.3 million cubic meters of the treated wastewater can start from Thursday and will likely continue over at least the next three decades.

“The Japanese government insists on discharging nuclear wastewater into the sea,” Lee wrote in a Facebook post. “This unprecedented decision and practice of discharging a large amount of nuclear waste over 30 years — regardless of the inextricable risks to food safety and the irreversible pollution and damage to the marine environment — is an irresponsible imposition on others.”

The release has become a geopolitical flashpoint with China and other nations questioning the proposal’s safety. Macau is also covered by the ban, officials said at a press conference in Hong Kong on Tuesday. They added that the two Chinese special administrative regions will test Japanese products daily.

Kishida has insisted that Japan will meet safety standards, and that similar releases of wastewater are relatively commonplace in the nuclear sector. A two-year review by the International Atomic Energy Agency found Japan’s strategy would have a negligible impact on people and the environment.

Hong Kong was the second-largest importer of Japanese seafood such as fish and shellfish after mainland China last year. The city imported some 75.5 billion yen ($518 million) worth of marine delicacies.

The Hong Kong ban extends to products from 10 Japanese prefectures — including Tokyo and Fukushima, along with some landlocked regions — and includes “all live, frozen, chilled, dried, or otherwise preserved aquatic products, sea salt and unprocessed or processed seaweed.”

It doesn’t mark a blanket ban against Japanese seafood — other prefectures not included in the list of 10 have significant fishing industries. Even so, Hong Kong businesses have been bracing for impact from the curbs, even prompting some restaurants to begin looking for new suppliers.

People became concerned about food safety once Japan’s intentions became public, said Simon Wong, president of Hong Kong Federation of Restaurants and Related Trades. Japanese restaurants have already seen business fall this year by up to 30% as of August, which implies losses for the industry of as much as HK$10 billion ($1.3 billion) should that be sustained for the rest of 2023.

Chinese Foreign Ministry spokesman Wang Wenbin urged Japan to cancel its release and disposal plan in a responsible manner after consulting with neighboring countries — though he did not identify any specific actions that the nation might take. The country purchased 87.1 billion yen worth of aquatic products from Japan last year.

“It’s extremely selfish and irresponsible for Japan to transfer the risks of nuclear contamination to the rest of humanity,” Wang said at a press briefing in Beijing on Tuesday. “The ocean sustains humanity and we should not allow Japan to dump nuclear contaminated water into it.”

South Korea’s main opposition party on Tuesday labeled the planned discharge the “worst environmental destruction,” and denounced President Yoon Suk Yeol over his government’s backing of Japan on the issue.

“This is a complete dereliction of duty to protect the lives and safety of the people,” Democratic Party of Korea leader Lee Jae-myung said, Yonhap News reported. The Korea Federation for Environmental Movements held a protest in front of the Japanese embassy in Seoul.