The leaders of member states of the Association of Southeast Asian Nations have responded calmly to the Japanese prime minister's explanation about the safety of treated and diluted water being released from the Fukushima Daiichi nuclear plant into the sea.

Prime Minister Kishida Fumio made the explanation to the leaders and those from China and South Korea at the ASEAN Plus Three Summit in Jakarta on Wednesday.

China's state-run news agency Xinhua reported that Premier Li Qiang in response asked Japan to handle the matter responsibly.

Indonesia's Trade Minister Zulkifli Hasan told reporters that Japan guarantees the safety of the water, so he sees no problem.

A Thai foreign ministry official told NHK that Japan provided a clear explanation based on internationally recognized scientific standards.

Kishida also explained the safety of the water at his separate meeting with Malaysian Prime Minister Anwar Ibrahim on Wednesday.

Japanese government officials said Anwar expressed understanding of Japan's position.

The Fukushima Daiichi nuclear power plant suffered a triple meltdown in the 2011 earthquake and tsunami. Water used to cool molten fuel at the plant has been mixing with rain and groundwater.

The accumulated water is treated to remove most radioactive substances, but still contains tritium. Before releasing the treated water into the sea, the plant's operator dilutes it to reduce tritium levels to about one-seventh of the World Health Organization's guidelines for drinking water.