Chief Executive John Lee on Tuesday appointed Andrew Kan as the new head of the police force's national security department.

Kan replaces deputy police commissioner Edwina Lau who has just retired.

The city's leader said in a statement that Kan, who has been with the force for 32 years, has demonstrated "outstanding performance, professionalism and an exemplary commitment to serve".

"He has a high awareness of national security and is familiar with national security affairs," Lee said.

Steve Li, senior superintendent of the national security department, has been promoted to chief superintendent.

"He has displayed loyalty and dedication as well as unwavering commitment to discharging his duties in safeguarding national security, resulting in outstanding accomplishments," the CE said in his statement.

"Even though both [Kan] and [Li] face the United States' bullying act of gross imposition of so-called 'sanction', they are fearless, firm and dedicated to their duties. I recognise their work and have confidence that they will take on more responsibilities in their new positions and make greater contributions to safeguarding national security," Lee added.

Assistant commissioner of police Kelvin Kong, meanwhile, has been promoted to senior assistant commissioner to succeed Kan as director of national security.

"[Kong] has remained steadfast in carrying out his duties in safeguarding national security and has delivered outstanding performance. I am confident that [Kong] will make greater contribution in his new position," Siu said.