TOKYO: Japan will release more than a million tonnes of treated water from the stricken Fukushima nuclear plant into the ocean, the government said Tuesday, triggering a furious regional reaction and fierce opposition from local fishing communities.

The process is not likely to begin for several years and could take decades to complete, but China quickly slammed the decision as “extremely irresponsible” and South Korea summoned the Japanese ambassador.

Japan’s government argues the release is safe because the water is processed to remove almost all radioactive elements and will be diluted.

The International Atomic Energy Agency (IAEA) has endorsed the release, which it says is similar to the disposal of wastewater at nuclear plants elsewhere.

Prime Minister Yoshihide Suga told a ministerial meeting that disposing of the water was an “inevitable task” in the decades-long process of decommissioning the nuclear plant.

He said the release would happen only “after ensuring the safety levels of the water” and alongside measures to “prevent reputational damage”.

Around 1.25 million tonnes of water have accumulated in tanks at the nuclear plant, which was crippled after going into meltdown following the 2011 tsunami.

It includes water used to cool the plant, as well as rain and groundwater that seeps in daily.