A passenger plane thought to have been struck as it approached Heathrow airport was probably not hit by a drone after all, the government says.
Transport Secretary Patrick McLoughlin told MPs it was now thought what happened "was not a drone incident".
Air accident investigators said they had not ruled out a drone but had no evidence to support the suggestion.
An investigation was launched after the pilot of a BA flight from Geneva on 17 April said an object struck the plane.
At the time the Metropolitan Police said the plane was flying at about 1,700ft (580m) over the area of Richmond Park, in south west London, at the time of the incident.
By Richard Westcott, BBC Transport Correspondent
Even if the Heathrow drone strike wasn't a drone at all, and we'll never know for sure, the near misses are coming at an alarming rate.
The latest statistics show that on Valentine's Day, a drone came within 20 to 150ft of an Airbus A320 near Biggin Hill in Kent. The British Airways plane was flying at 12,500 feet. Drones are not meant to go above 400ft.
The crew reported it was "six feet wide with a red flashing light". It was all over in seconds, there was no time to react and they never found the drone operator.
There were 40 drone near misses in 2015 and just nine the year before. Hence the calls for urgent action to prevent an accident.
Many pilots feel it is a matter of time before a drone hits a plane, and they simply don't know what will happen if it does.
But BBC Transport Correspondent Richard Westcott said air accident investigators had stopped their investigation because "there is nothing to look at".
Our correspondent said the item, which struck the front of the aircraft, could have been "floating debris".
"They just don't have any evidence to tell them one way or the other," he added.
The Airbus A320 was carrying 132 passengers and five crew as it approached the airport. It landed safely.
The incident had been thought to be the first drone collision with an aircraft in the UK.
Drone incidents at UK airports
- 17 April 2016 - A British Airways plane approaching Heathrow is believed to have hit a drone while in midair
- 28 November 2015 - The pilot of an A321 plane narrowly missed a drone hovering at 100ft above a runway at Gatwick Airport
- 30 September 2015 - A small drone helicopter passed within 30ft of the cockpit of an A319 plane while on the approach to Heathrow
- 22 September 2015 - A "quadcopter-type drone" missed the right-hand side of a B777 plane by about 25m while at 2,000ft after it left Heathrow Airport
- 13 September 2015 - A silver drone with a "balloon-like" centre missed an E170 aircraft by about 20m, while the plane was approaching London City Airport over the Thames
- 13 September 2015 - A drone flew over the top of a B737 aircraft while at 4,000ft, missing it by about 5m, shortly after it left Stansted
- 27 August 2015 - A DO328 aircraft flew within 50ft of a drone while approaching Manchester Airport at 2,800ft
Source: The UK Airprox Board
The UK Air Proximity Board - which investigates near-miss incidents in UK airspace - says there had been a number of serious near-misses at UK airports involving drones.
The head of the International Air Transport Association, Tony Tyler, earlier this year warned that drones flown by the general public were "a real and growing threat" to civilian aircraft.