Under the rules, introduced after a legal challenge by a police union, only journalists who are registered to receive government press releases from the Information Services Department will be able to study the electoral rolls.

The HKJA says it's concerned that this could be a backdoor way to implement an official registration system for the media – something pro-Beijing groups have called for in recent months.

In response, the Registration and Electoral Office said it respected the freedom of the press and its role in monitoring the election process.

It said almost 200 new media organisations from Hong Kong and elsewhere were registered with the ISD, and the restrictions were based on practical considerations rather than being an attempt to narrow the definition of the media.

The move follows a court challenge by the Junior Police Officers' Association, which complained that allowing the public access to electoral registers raised the possibility of people releasing the information of police or their officers online.

The Court of Appeal partially upheld that challenge, agreeing that the media and political parties could have access to the registers but not the general public.