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 April 17 said an object struck the plane.
The Metropolitan Police had said the plane was flying at about 1,700ft over the area of Richmond Park, in south west London, at the time of the incident.
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The incident had been thought to be the first drone collision with an aircraft in the UK.
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 latest statistics from the board showed there was another drone near miss on February 14 with an Airbus A320 that was flying out of Heathrow at 12,500ft.
The crew reported missing the 6ft wide black drone, which had a flashing red light, by 20ft.
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.