Police are investigating reports two planes flew underneath a landmark Highland bridge in an alleged daredevil stunt.

Police who are investigation the reports say the possible 'unofficial aeronautical acrobatics' occurred at the Kessock Bridge in Inverness on Tuesday afternoon and the facts have been reported to the Civil Aviation Authority.

Two planes were witnessed flying under the bridge carrying the A9 over the Moray Firth, before meeting up with a third one.

Witness Norman Macleod told the police in an online post: "I saw the planes, two had single wings and the other looked like it was a biplane. I remember thinking is it not illegal to fly under it?"

A Police Scotland spokesman said: "Two of the planes were reported as having flown beneath the bridge before meeting up with the third plane and continuing on their flight path. Enquiries are ongoing."

A Civil Aviation Authority spokesman said they needed photographic evidence. He said: "We are aware that reports have been made to the police but we are not investigating yet because nothing has been formally reported to us. We need evidence."