The International Atomic Energy Agency and experts from China, South Korea and Canada on Monday collected seawater samples near the crippled Fukushima nuclear complex in northeastern Japan following the release of treated radioactive water from the site, the Japanese government said.

The team is visiting Japan through Oct. 23 to corroborate the country's marine monitoring amid safety concerns over the water release, which began late August. China has sharply reacted to the discharge by imposing a blanket ban on Japanese seafood imports.

In addition to seawater, the team will collect samples of seabed sediment and fish and compare the levels of tritium and other radioactive substances from those taken last year, according to Japan's Nuclear Regulation Authority.

Photo taken from a Kyodo News helicopter shows the crippled Fukushima Daiichi nuclear power plant on Aug. 22, 2023. (Kyodo)

The NRA said the experts from China, South Korea and Canada have been nominated by the IAEA and their activities are expected to provide "further transparency" for Japan's sea monitoring efforts.

The water discharge is seen as a key step to advance the decommissioning of the Fukushima Daiichi plant, which suffered triple reactor fuel meltdowns following a catastrophic earthquake and tsunami in 2011. The wastewater has gone through a liquid processing system that removes most radionuclides except tritium.

The Japanese government has pledged the safety of the water release, to continue for three decades, noting it is diluted to reduce the tritium levels to less than one-40th of the concentration permitted under national safety standards before being released into the Pacific Ocean.

No abnormal levels of tritium and other radioactive substances have been detected in seawater or fish samples collected from around the nuclear plant since the first round of water discharges running from Aug. 24 to Sept. 11, according to monitoring by the Japanese authorities, plant operator Tokyo Electric Power Company Holdings Inc. and the IAEA.

Still, some countries and local fishermen in Fukushima Prefecture have criticized the Japanese government's decision. Beijing has repeatedly urged Japan to halt the plan, calling the water "nuclear-contaminated."

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