A passenger jet came alarmingly close to colliding with two unmanned drones in the skies above London in the first recorded incident of a plane nearly striking one of the unmanned gadgets.

An Airbus A320 was flying at 5,500ft over east London preparing to land at Heathrow Airport when its flight crew spotted two white drones on 20 November 2016.

Pilots of the aircraft, which can carry 150 passengers "remained in constant visual contact" with the drones which would have "compromised the safety of the aircraft", according to an investigation by the UK Airprox Board (UKAB).

The UKAB report said the there would have been a "significant risk of collision" if the plane was on a different approach path to Heathrow, one of the pilots said to investigators.

It is estimated the drones came within 500 metres of the aircraft.

Then, less than 30 minutes later, a Boeing 777 approaching the same airport reportedly flew within 50 metres of what is believed to have been one of the white orb-like gadgets that was roughly 2 metres wide and had four prongs.

A report was made to the Metropolitan Police, but the drone operators could not be located.

Drones have been used by criminals increasingly to deliver drugs to prisons and by prisoners to "scope out" properties before they are targeted.

British Airways Airbus A320
File photo: An Airbus A230 almost collided with two drones over London, said a new report. iStock

The Civil Aviation Authority (CAA) said this was the first aircraft near-miss involving more than one drone.

In a monthly report, UKAB reported that there were five near-misses between aircraft and drones with 62 incidents over the last year.

Earlier this month another incident involving a drone was reported to police after a drone was reportedly close to an airplane heading to Heathrow.

The CAA printed new guide lines in November last year, named the Dronecode, the rules state that drones must not be flown above 400ft (122m) or near airports or airfields.

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File picture. An Airbus A320 was flying at 5,500ft over London when it was spotted by flight crew. Getty Images

In 2016 UKAB reported two near-misses between drones and passenger planes at Heathrow and Manchester airports.

According to a pilot, a drone helicopter passed less than 30 metres from his A319 in the middle of his flight path when heading to Heathrow.

And in Manchester, a red and white drone was spotted less than 15 metres away from a passenger plane, it was reported.