Tokyo is urging Beijing to try to lower the temperature on a contentious issue. Japanese organizations in China have faced a backlash since Japan started releasing treated and diluted water from a nuclear power plant into the sea. People in Japan are also being targeted.

Some facilities in Japan unrelated to the release have been getting harassing phone calls from overseas. The country code on the calls suggests most have originated in China.

Posts on Chinese social networking services ask readers to condemn Japan for releasing what they call "nuclear contaminated water." They also provide Japanese phone numbers for people to call to make complaints.
Several incidents have been reported in China. A stone was thrown onto the grounds of a Japanese school in Qingdao, Shandong Province, on Thursday, the day the treated water release began. And eggs were hurled into the compound of another school in Suzhou, Jiangsu Province the next day. The schools' operators say there was no damage.

Japan's Foreign Ministry has urged Japanese nationals living in or planning to visit China to exercise caution. That includes avoiding speaking loudly in Japanese while in public, and staying away from any protests.

Japan's Chief Cabinet Secretary Matsuno Hirokazu said: "We strongly urge the Chinese government to take all possible measures to ensure the safety of Japanese residents and our diplomatic missions in the country, and to provide accurate information about the treated water. We are going to keep urging the government to do so."

Beijing has intensely criticized the water release. Last Thursday, it suspended all Japanese seafood imports in response.

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.

Japan's Environment Ministry released the first results of its post-release seawater testing on Sunday.

It measured less than 10 becquerels of tritium per liter at all locations, the minimum level the government says is detectable.