Japan has lodged a protest with China and Russia over how a joint statement by the two countries' leaders refers to treated and diluted water released into the ocean from the crippled Fukushima Daiichi nuclear power plant.
The statement signed by Russian President Vladimir Putin and Chinese President Xi Jinping on Thursday described the water as "nuclear contaminated" and expressed serious concerns. The two leaders held summit talks in Beijing on the day.
Japan's Chief Cabinet Secretary Hayashi Yoshimasa told reporters on Friday that the two countries' inaccurate reference about the release of the treated and diluted water is very regrettable.
He said the Japanese government lodged a protest with both Chinese and Russian sides through diplomatic channels immediately after the release of the document.
Hayashi said the water discharge is consistent with international safety standards, and Japan is disclosing relevant monitoring data swiftly and with a high degree of transparency.
He added that such efforts have gained understanding and support widely from the international community. He said the government will continue to explain Japan's efforts and disclose monitoring data to China and Russia thoroughly and with transparency.
The Fukushima Daiichi nuclear power plant suffered a triple meltdown following 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 ocean, the plant's operator dilutes it to reduce tritium levels to about one-seventh of the World Health Organization's guidance level for drinking water.