A Taiwanese scholar who has been missing since entering mainland China last year is being investigated on suspicion of activities endangering national security, mainland media reported on Wednesday.

Tsai Chin-shu, head of an association that promotes relations between Beijing and Taipei, disappeared in July 2018 after travelling to Xiamen, Fujian province, according to Taiwanese media.

Ma Xiaoguang, spokesman of the State Council Taiwan Affairs Office, disclosed on Wednesday that Tsai was being investigated “for suspected activities endangering national security”, according to the China News Service.

Tsai is the chairman of the South Taiwan Cross-Strait Relations Association.

It is the second such case to come to light in recent weeks.

Earlier this month, Beijing confirmed that Lee Meng-chu – a Taiwanese man who went missing after crossing into the mainland from Hong Kong in August – was being investigated for activities that endanger state security.

Another Taiwanese man, democracy activist Lee Ming-che, was sentenced to five years in prison by a mainland court in November 2017 on charges of subverting state power. (AFP)