Japan is "closely monitoring" the case of a Chinese professor working for a Tokyo university who went missing last year while visiting his home country, raising concerns about a potential human rights issue, the top government spokesman said Monday.

Chief Cabinet Secretary Yoshimasa Hayashi confirmed recent reports that Fan Yuntao of Japan's Asia University remains unaccounted for.

File photo shows Fan Yuntao, a Chinese professor of Japan's Asia University, in Yangzhou, China, in September 2018. (Kyodo) 

"This is a matter that could be related to the human rights of the professor, who has been engaging in education at a Japanese university for years," Hayashi said at a regular press conference but declined to elaborate further on the matter, citing its sensitive nature.

In late February 2023, Fan temporarily returned to Shanghai. Before he went missing, he told people around him that he was asked to accompany authorities for interrogation, sources familiar with the bilateral relationship have said, adding he may have been detained.

Fan, an expert in international law and politics, had intended to return to Tokyo by April last year, but his family, residing in Japan, has yet to establish contact with him, according to the sources.

Chinese Foreign Ministry spokesman Wang Wenbin said at a press conference Monday in Beijing he is "not aware of information" related to Fan.

His disappearance has drawn attention as China has been strengthening its efforts to safeguard national security, leading to detentions of people, including foreign nationals, on suspicion of engaging in spying activities.

Beijing's intensifying crackdowns on foreigners and Chinese people interacting with other countries are expected to deepen strains in Sino-Japanese ties, which are already frayed by several issues, including territorial disputes.

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