A group of Japanese academics are voicing concern over China's recent detention of one of their colleagues.
Japan's foreign ministry says a man in his 40s was taken into custody last month, while visiting Beijing.
The Hokkaido University professor is an expert on Chinese history and had been invited into the country by the Chinese Academy of Social Sciences.
The group, including professor emeritus at Waseda University Satoshi Amako and Hosei University professor Masaharu Hishida, released a statement on Tuesday.
It called news of the detention shocking beyond words.
The statement warned that the situation could undermine academic exchanges, saying news of cancelled trips to China is already spreading among scholars.
It also called on Chinese authorities to disclose details of what led to the detention.
So far, all that's known is that the man allegedly violated Chinese law -- but there's no word of any charges.
Over the past five years, 13 Japanese nationals have been detained in China.
Of those, nine were indicted on suspicion of spying.