Cargolux has grounded a Boeing 747-400 freighter which was struck by small-arms fire, resulting in a bullet hole in the fuselage.
The airline said the hole was found during a maintenance A-check on the 747 after it returned from a multiple-stop African service.
It operated the flight on 4 July, flying from Luxembourg to Abidjan in Ivory Coast, then Accra in Ghana, and finally to the Nigerian city of Abuja before returning to its home base on 5 July.
"The hole was found in an unpressurised area on the left side near the rear of the aircraft and did not endanger the safety of the crew at any time," said Cargolux.
While it has determined that the hole "was caused by a bullet" it added that there is "no evidence" that the aircraft was shot at deliberately - although it also said this "cannot be ruled out".
It has filed incident reports with the Luxembourg police service and the country's civil aviation authority. Cargolux operates 16 747-400 freighters.