Chinese authorities have detained a Japanese man in Beijing, Tokyo confirmed Monday, following media reports that a university professor was being held on suspicion of spying.
"The Japanese embassy in China confirmed that a Japanese man in his 40s was detained by Chinese authorities in Beijing in September for (allegedly) violating Chinese laws," Japan's top government spokesman Yoshihide Suga told reporters.
He did not specify the charges against the man, but Japanese media have identified him as a professor from Hokkaido University who was held on suspicion of spying.
The man, who has not been named, worked previously for the National Institute for Defense Studies in the defence ministry and the Japanese foreign ministry, according to local media reports.
"Within the framework of protecting Japanese expatriates, we are holding meetings between (the man and) consuls and communicating with his family members, but we decline to comment on further details given the nature of this case," Suga said.
In Beijing, Chinese foreign ministry spokeswoman Hua Chunying said she did not know the details of the case, but that China "has always handled foreign nationals suspected of breaking China's law, in accordance with the law."
China will "provide the necessary assistance in order for the Japanese side to perform the normal consular duties, in accordance with the relevant provisions," Hua said at a regular press briefing.
Hua said the detention was a "one-off case".
"We hope that the Japanese side can remind its citizens to respect China's laws and regulations, and avoid engaging in illegal activities in China," she said.
But, she added, China is "willing to work together with Japan to promote the continued progress of China-Japan relations along the correct path" and that "these are two completely separate issues".
She noted that Chinese Vice President Wang Qishan is scheduled to attend the enthronement of Japan's Emperor Naruhito on Tuesday.
China has faced accusations of using detentions of foreigners as a political tool, including recently from Canadian Prime Minister Justin Trudeau who called it "hostage diplomacy".
Canada-China ties have soured since its arrest of Chinese Huawei executive Meng Wanzhou on a US warrant last December -- nine days later, Beijing detained two Canadians and months later accused them of espionage-related activities.
The two Canadians are among a string of foreign nationals arrested in China and charged with espionage or attempting to steal state secrets.
Australian academic Yang Jun, who also goes by his pen name Yang Hengjun, was detained in January shortly after making a rare return to China from the US. Beijing said in September that he had been formally arrested on suspicion of spying.
China also detained six Japanese citizens in 2017 for alleged "illegal activities".
Since 2015, at least 13 Japanese citizens -- all civilians -- have been detained in China on various charges including espionage, Japan's Kyodo News and the Asahi Shimbun reported.
Tokyo's ties with Beijing have been at times strained by rows over history and territorial disputes but have been improving recently, with President Xi Jinping expected to visit Japan early next year.