The Police Ombudsman's Office has appealed for information about an incident in Portadown during which a police officer discharged CS Spray.
The incident, during which a police officer was struck with a hammer, happened at about 9am on Sunday 24 October at Thomas Street in the town.
A spokesman said: "We would like to hear from anyone who witnessed the incident, and who can tell about the circumstances in which the CS Spray was discharged."
The Chief Constable of the PSNI referred the incident to the Police Ombudsman for investigation. All discharges of CS Spray in Northern Ireland are currently investigated by the Police Ombudsman's office, following a request from the PSNI.
Anyone who witnessed the incident is asked to contact the Police Ombudsman's Office on 028 9082 8695.
ENDS