Hong Kong police said Wednesday they had arrested a man suspected of an attack on a Japanese couple which prompted Tokyo to warn its 22,000 citizens in the city to avoid going out at night.
The incident, which occurred Monday evening as the pair were taking a stroll on a busy waterfront, comes as tens of thousands of anti-Japan protestors rallied across China in recent days over a territorial row.
According to a police spokeswoman, the couple, aged 37 and 35, were repeatedly punched by a local man who has since been released on bail.
"The man attacked the couple and fled the scene," the officer told AFP.
"Police had arrested a 31-year-old Hong Kong man late Tuesday and questioned him for assault and causing actual bodily harm," she said, adding the man will be required to report back to the station later this month.
The attack prompted the Japanese consulate to issue a safety warning to its citizens, urging them to avoid moving in groups and going out at night.
"We have asked the Hong Kong authorities to ensure the safety of our citizens in Hong Kong," Miyuki Matsumoto, the Japanese public relations consul in the city, told AFP.
According to local media, the man asked the couple whether they were Japanese before he assaulted them.
It was the first case of violence reported in the semi-autonomous city following nationwide demonstrations in recent days over disputed islands in the East China Sea known as Senkaku in Japan and Diaoyu in China. They are also claimed by Taiwan.
Japanese firms including Canon, Panasonic and Honda Motor had temporarily shut all or part of their operations in China due to safety concerns.
Hong Kong activists have also staged anti-Japan rallies in recent weeks but they had been largely peaceful.