A Japanese Cabinet minister has visited the national federation of fisheries cooperatives to ask again for understanding of the planned release of treated and diluted water from the crippled Fukushima Daiichi nuclear plant.

Industry minister Nishimura Yasutoshi met Sakamoto Masanobu, president of JF Zengyoren, at its office in Tokyo on Friday. The group opposes the government's plan to discharge the water into the sea.

Nishimura said it is necessary to deal with the accumulation of treated water in the process of decommissioning the plant and rebuilding Fukushima.

He said the government will work responsibly with the plant's operator to ensure safety in dealing with the issue.

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

Sakamoto said his organization maintains its opposition to the plan at this point, but also thinks the problem of the plant will not be over until it is decommissioned.

JF Zengyoren said Nishimura explained during the meeting with Sakamoto the contents of a comprehensive report on the plan's safety by the International Atomic Energy Agency.

The meeting with Sakamoto took place after Nishimura attended a meeting with the Fukushima Prefectural Federation of Fisheries Cooperative Associations in Iwaki City on Tuesday. The local group also opposes the plan.

Sakamoto later told reporters that he thinks he could understand the safety of the plan to a certain degree on a scientific basis, but also said safety in science and security in society are different things.

He said unless fishery workers in his group feel relieved, it cannot drop its opposition to the plan.

The government plans to dilute the water to reduce tritium levels to about one-seventh of the World Health Organization's standard for drinking water quality. It plans to start releasing the water around summer this year, and officials are considering concrete dates.