BEIJING (AP) — Chinese authorities refused to allow Canadian diplomats to attend the trial of a Chinese-born Canadian tycoon who disappeared from Hong Kong five years ago, Canada’s government said Tuesday.

Xiao Jianhua was last seen at a Hong Kong hotel in January 2017 and is believed to have been taken to the mainland by Chinese authorities. The government has never confirmed whether he was detained or what charges he might face.

The Canadian government said earlier Xiao was due to stand trial Monday but gave no indication whether a trial took place or where. It gave no details of possible charges.

“Canada made several requests to attend the trial proceedings. Our attendance was denied by Chinese authorities,” a Canadian government statement said.

Xiao, the founder of Tomorrow Group, vanished amid a flurry of prosecutions of Chinese businesspeople accused of misconduct.

That fueled fears the ruling Communist Party might be abducting people outside the mainland. Hong Kong at that time prohibited Chinese police from operating in the former British colony, which has a separate legal system.

Since then, Beijing has tightened control over Hong Kong, prompting complaints it is violating the autonomy promised when the territory returned to China in 1997. The ruling party imposed a national security law in 2020 and has imprisoned pro-democracy activists.

Hong Kong police investigated Xiao’s disappearance and said the subject crossed the border onto the mainland. But an advertisement in the Ming Pao newspaper in Xiao’s name the same week denied he was taken against his will.