Secretary for Environment and Ecology Tse Chin-wan says Hong Kong will have no choice but to continue to ban aquatic products from 10 Japanese prefectures if the country goes ahead with a plan to release more wastewater from the tsunami-crippled Fukushima nuclear plant on Thursday.

"So far, Japan has failed to convince us with regard to the long-term cumulative impact of releasing wastewater into the ocean," Tse said on Wednesday.

"Unless Japan discontinues the practice of discharging wastewater into the ocean, or adopts better measures to ensure safety, we are left with no alternative but to maintain the ban."

The minister said the import restrictions have not had a substantial effect on Hong Kong's food supply, and clearance times for Japanese food products have not lengthened.

He said Hong Kong has also proposed acting as a "third-party monitor" regarding the release of the wastewater, but Tokyo has not responded to the suggestion.

Japan says the discharge from Fukushima is safe, a view backed by the UN atomic agency.