Hong Kong operates under a common law jurisdiction separate from mainland China and invites overseas judges to hear cases at its Court of Final Appeal.

Their presence has been seen as a bellwether for the rule of law since the former British colony was handed back to China in 1997.

Five overseas judges have quit the city's top court without finishing their terms since Beijing passed a sweeping national security law in Hong Kong in 2020. Four others have not renewed their appointments.

British judge Jonathan Sumption resigned in June after saying Hong Kong's "rule of law is profoundly compromised", shortly after 14 pro-democracy activists were convicted of subversion.

Hong Kong authorities argued that the city remained a well-respected legal hub and that the security law was necessary to restore order after huge protests in 2019.

Chief justice Andrew Cheung said on Monday foreign judges were deterred from serving in Hong Kong not because of the security law, but because the role had become "politicised".

"Given the current geopolitical headwinds, recruiting overseas judges with the right stature and experience may be less straightforward than it once was," he said at a ceremony opening the city's legal year.

Cheung said overseas judges wanting to work in Hong Kong have been subjected to "orchestrated harassment and pressures", which he called "deplorable" and partly blamed on media reporting.

Cases at Hong Kong's top court are typically heard by a panel of four local judges and a fifth ad hoc member, who may be a foreign judge.

Two national security cases that reached the court in recent weeks were heard by an all-local judges bench.

Cheung said he was "reasonably confident of keeping our existing (overseas judges)" as well as recruiting new ones.

The Court of Final Appeal, which once boasted 15 overseas judges, is now down to six -- including 90-year-old Leonard Hoffmann, whose term was renewed this month.