Air traffic controllers have been left baffled by a plane which left a bent contrail in the sky, suggesting it suddenly changed its path mid-air.

Teacher Florence Lehmann spotted the plane’s trail, which resembles a ditch, as she left her home in Southsea, Hampshire at around 7:20am on Monday.

Miss Lehmann said: "It's really weird. It looks like the pilot sneezed or fell asleep. Somebody said a UFO had been spotted recently in the area and the pilot had tried to avoid it, which I quite like the sound of.

"There was no wind this morning and the plane actually moved trajectory."

A spokeswoman for Nats, the air traffic control company, said she was unable to explain why the plane had apparently changed direction.

The unusual contrail (Florence Lehmann/PA Wire) (Florence Lehmann /PA Wire)

She said: "Unfortunately Nats has no knowledge of the purpose of any given flight and we do not identify individual aircraft to members of the public."

The mystery comes after a grey-spherical object was photographed in the skies above Portsmouth last week. Some believed it may have been a UFO, as the Met Office reportedly said it was not linked to the weather.