Japan's embassy in Beijing said on Thursday it had warned its nationals living in China to be vigilant, as a row over Tokyo's arrest of a Chinese boat captain in disputed waters rumbled on.
The warning from the embassy, posted on its website, came amid reports that anti-Japanese protesters could take to the streets on Saturday in both Beijing and Shanghai to press for the release of the captain.
"We warned Japanese nationals living in China as well as those travelling and doing business here, through emails and our website, that they should take care of their safety," an embassy press officer told AFP.
The Japanese official, who asked not to be named, said the embassy had no specific information that a demonstration would take place outside the mission on Saturday, and had received no guidance from Chinese police.
Beijing and Tokyo are entangled in their worst diplomatic spat in years, stemming from the collision last week of a Chinese fishing trawler and two Japanese coastguard vessels near a disputed island chain in the East China Sea.
China has so far summoned Japan's ambassador five times over the incident, and demanded the unconditional release of the captain. Japan says the skipper intentionally rammed the Japanese patrol vessels during a high-seas chase.
A notice posted on the embassy's website said police had told Tokyo they would "do their utmost to ensure the safety of Japanese nationals".
The statement, dated Wednesday, urged Japanese citizens living in China to "use caution in words and attitude when engaging with Chinese individuals" and refrain from carrying out "noticeably provocative actions".