The UN's nuclear watchdog says Japan's discharge of treated and diluted water from the crippled Fukushima Daiichi nuclear power plant into the ocean continues to meet international safety standards.

A task force of the International Atomic Energy Agency issued a report on Thursday based on its second mission to Japan since the water discharge began in August last year.

The task force reaffirmed the conclusions from the IAEA's comprehensive safety report issued before the release operation began. The pre-release report said Japan's handling of the treated water is consistent with international safety standards. It also said that if the discharge proceeds as planned, the impact of radiation on humans and the environment would be negligible.

The new report was compiled based on findings of the task force's mission to Japan in April involving experts from nine countries including the US, South Korea and China.

The report says the task force did not find any deviations from international safety standards.

It noted that during their inspection, there was an automatic suspension of the water release due to the loss of on-site power. It added that this automatic suspension was within design specifications and no abnormalities were identified in the equipment, and that the discharge restarted on the same day.