Tokyo has urged Beijing to "ensure the safety of Japanese residents in China" after a wave of telephone harassment targeting businesses in Japan sparked by the controversial discharge of Fukushima wastewater.
While Japan insists the release of the treated water is safe -- a view backed by the U.N.'s nuclear watchdog -- China has staunchly opposed it and banned all Japanese seafood imports, saying it contaminates the ocean.
The Japanese government on Sunday published new data showing waters off Fukushima continued to post radioactivity levels well within safe limits.
Calls from China began flooding Japanese businesses from Thursday, when operator TEPCO started releasing water used to cool the stricken nuclear reactors at Fukushima Daiichi nuclear plant.
Japanese businesses and groups, ranging from a concert hall in Tokyo to an aquarium in northern Iwate, reported that they had started receiving so many calls from Chinese speakers that they had difficulty conducting normal operations.
Hiroyuki Namazu, a senior Japanese diplomat in charge of Asian and Oceanian affairs, voiced his regret about the calls and told senior officials at the Chinese Embassy in Tokyo to call for calm in China, the Japanese foreign ministry said in a statement late Saturday.
Similar incidents have also occurred in China against Japanese facilities, Namazu told Chinese Embassy officials, according to the statement.
"We strongly urge the Chinese government to take appropriate measures, such as calling on its citizens to act calmly, and to take all possible measures to ensure the safety of Japanese residents in China and Japanese diplomatic missions in China."
Tokyo's embassy in Beijing has separately urged its nationals there to refrain from speaking loudly in Japanese.
A Fukushima businessperson told the Kyodo news agency that his four restaurants and pastry shops received a total of about 1,000 calls on Friday, mostly from China.
His businesses had to unplug their phones, Kyodo said.
Fukushima city mayor Hiroshi Kohata said in a Facebook post Saturday that the city hall had received around 200 similar calls in two days, while local schools, restaurants and hotels also became targets.
"I will report this to the Japanese government and demand action," he wrote in his post.
Chinese social media users shared videos of themselves making calls to Japanese numbers, including restaurants in Fukushima.
TEPCO is releasing more than 500 Olympic swimming pools' worth of wastewater used to cool Fukushima's damaged reactors, three of which went into meltdown in March 2011 when they were hit by a massive earthquake and tsunami that killed about 18,000 people.
The water has been filtered of all radioactive elements except for tritium.
The Japanese environment ministry said Sunday that a fresh test of Fukushima coastal water showed no elevated levels of tritium.
The ministry added that the water samples did not show signs of gamma radiation that can come from other radioactive materials such as caesium.
