A PSNI officer is facing disciplinary action for leaving a gun behind after a house search.
Police had raided the property in the Ardoyne area of north Belfast and arrested a 39-year-old man on suspicion of dissident republican activity.
It is understood the firearm and ammunition was left in a child's bedroom, though there were no children in the house at the time.
Upon realising the weapon was missing, police said they returned to the house and retrieved it 20 minutes later.
A PSNI spokesman said the incident was being treated very seriously.
"After the search an item of officer's personal equipment, a gun belt which included a firearm, was discovered missing," he said.
"Police returned to the address after approximately 20 minutes and with the consent of the householder retrieved the item.
"Police are treating the temporary loss of this equipment extremely seriously and have commenced an internal disciplinary investigation into the circumstances of the incident."
PA