The Japanese fisheries federation has again voiced its opposition to the planned release of treated and diluted water from the crippled Fukushima Daiichi nuclear plant into the sea.

Sakamoto Masanobu, president of JF Zengyoren, the national federation of fisheries cooperatives, handed over a request opposing the release to Industry Minister Nishimura Yasutoshi on Thursday.

Water used to cool molten nuclear fuel has been building up at the plant. It mixes with rain and groundwater and is treated to remove most radioactive materials, but some tritium remains.

The Japanese government plans to release the treated water after diluting it to reduce the tritium amount to about one-seventh of the level the World Health Organization deems safe for drinking water.

The plant's operator, Tokyo Electric Power Company, plans to start discharging the water into the ocean around this summer.

In the meeting, the fisheries federation president also urged the government to take thorough measures to prevent reputational damage to fishery products and to extend support to the local fishing industry.

Nishimura said that he understands the fishery workers' concerns, but releasing the treated water into the sea is unavoidable in the reconstruction of Fukushima.

The minister also said the government is committed to fully explaining safety measures as well as measures to prevent reputational damage so fishery workers can continue working without worries.

Speaking to reporters after the meeting, Sakamoto said Nishimura pledged to continue to provide details of the plan.

But Sakamoto said he told Nishimura that the federation's opposition to the discharge of the water will not change, and that the government should take complete responsibility.