A 38-year-old police officer has been arrested in the Sau Mau Ping area on suspicion of perverting the course of justice.
The case has been referred to the New Territories North Regional Crime Unit.
Media reports said the police are investigating if the arrested officer was involved in a case linked to suspected petrol bombs outside Kwai Chung Police Station.
In the April 13 incident, a suspect who allegedly carried the bombs was arrested.
Reports say the officer was in contact with the suspect before the incident.
The police said they attach great importance to the conduct of personnel and anyone who commits illegal acts will not be tolerated.