Beijing has told foreign consulates in Hong Kong to hand over personal details of all locally hired staff.
Local media report that a letter from the city arm of China’s Foreign Ministry asked for the data to be submitted by 18 October.
The requirements apply to all foreign missions’ local employees, including permanent residents and non-permanent residents in the financial hub.
The move would bring rules in Hong Kong into line with those in the mainland.
Hong Kong is part of China, but has had some autonomy since the end of British rule in 1997.
But following months of major demonstrations in 2019, Beijing tightened its control over the city by imposing a strict national security law outlawing many forms of dissent.
The law outlaws collusion with foreign governments.
Although already a requirement for Chinese employees of foreign embassies and consulates in the mainland, this is believed this is the first time such a policy is being implemented in Hong Kong.
The information to be submitted to Chinese authorities includes the staff’s job titles, residential addresses, and identity card numbers.
Consulates have also been asked to report new hires’ personal details within 15 days once they start at work, according to local media.
The letter stated that the collected data could be passed on to other authorities “for exercising their function in relation to managing the presence of the staff locally engaged”, the South China Morning Post reported.
The Commissioner’s Office of China’s Foreign Ministry in Hong Kong has not specified the purpose of the requirements.