South Korean authorities have found that two fighter jets collided mid-air in 2021 because the pilots were taking pictures and videos.

The incident took place while the jets were on a flight mission in the central city of Daegu, according to Seoul's Board of Audit and Inspection.

The pilots survived with no injuries, but the collision damaged the planes, costing the military 880 million won ($596,000; £440,500) in repairs.

One of the pilots, who has since left the military, was made to pay a fine of 88 million won.

The incident took place because that pilot had wanted to take photos to commemorate his last flight with his military unit.

Taking photos of significant flights was "a widespread practice among pilots at the time", the audit board said in a report published on Wednesday.

The pilot had declared his intent to do so in a briefing before the flight, according to the report.

He was flying the wingman aircraft and was following the lead aircraft during the mission. While flying back to their base, he started taking pictures using his personal mobile phone.

Upon noticing this, the pilot of the lead aircraft then asked another pilot on his plane to film a video of the wingman aircraft.

The wingman pilot then abruptly flew his jet up higher and flipped it so that it could be better captured on camera. This manoeuvre brought the two planes very close to each other.

To avoid a crash, the lead aircraft tried to rapidly descend. But the two F-15K jets eventually collided, damaging the lead aircraft's left wing and the wingman aircraft's tail stabiliser.

South Korea's air force suspended the wingman pilot, who has since left the military to work for a commercial airline.

Subsequently, the air force sought to fine the wingman pilot 880 million won to cover the full amount of the repair costs. When the pilot appealed against the fine, it prompted an investigation by the audit board.

The wingman pilot acknowledged his sudden manoeuvre led to the collision, but argued that the lead aircraft's pilot had "tacitly consented" to the manoeuvre since he was aware that filming was taking place.

The audit board eventually ruled that the wingman pilot should only pay a tenth of what the air force sought.

It said that the air force should bear some responsibility for not properly regulating pilots' personal use of cameras.

The board also took into account that the wingman pilot had a good track record prior to the incident, and that he had managed to prevent further damage by promptly commandeering a safe return of his aircraft to the base.

The report did not mention whether any action was taken against the other pilots involved in the incident.