A terrified pilot of a passenger jet has reported a near miss in which a rugby ball shaped UFO passed within a few feet of his aircraft while flying near Heathrow Airport, baffling aviation authorities in London.

The incident occurred while the plane was cruising at 34,000ft, around 32 km west of the airport, over the Berkshire countryside, The Telegraph reported. The captain spotted the object travelling towards the jet out of a left hand side, cockpit window, apparently heading directly for it.

The incident was investigated by the UK Airprox Board, which studies "near misses" involving aircraft in British airspace. It checked data recordings to establish what other aircraft were in the area at the time, but eliminated them all from its quest to find out what had been responsible. It also ruled out meteorological balloons, after checking none were released in the vicinity. Military radar operators were also contacted but were unable to trace the reported object.