The director general of the UN nuclear watchdog and South Korea's foreign minister have discussed Japan's plan to release treated and diluted water from the crippled Fukushima Daiichi nuclear power plant into the ocean.

International Atomic Energy Agency Director General Rafael Mariano Grossi met with South Korean Foreign Minister Park Jin in the South Korean capital, Seoul, on Saturday.

Ministry sources say Grossi briefed Jin on the IAEA's assessment of the plan during the meeting.

The IAEA review concluded that the treated and diluted water that Japan plans to release from the plant meets international safety standards.

Water used to cool molten nuclear fuel mixes with rain and groundwater. The water is then treated to remove most radioactive substances. But tritium remains.

Before the Japanese government releases the water into the ocean, it plans to dilute the water to reduce the level of tritium to about one-seventh of the World Health Organization's guidelines for drinking water quality.

The sources say Park asked Grossi to continue to cooperate, so that people in his country can feel secure about the safety of the treated water.

After the meeting, Park told reporters that he and Grossi had in-depth discussions about ways in which the IAEA and the South Korean government can work together to check and see if the water is safe.

On Friday, the South Korean government noted that its own assessment indicates the treated water from the plant will meet international safety standards, if it is released as currently planned by the Japanese government.

The South Korean government said it intends to accept the IAEA report.

There is growing concern in South Korea about the planned release. Groups protesting against it held a rally in Seoul on Saturday.

On Sunday, Grossi is scheduled to meet with lawmakers from South Korea's largest opposition party. They have been protesting against the plan.