Planes carrying a number of passengers came within 700ft of each other after instructions were given to the wrong aircraft, an inquiry has found.

The near miss incident happened to the north east of Southend on April 1, and involved a Boeing 737 leaving Stansted and Boeing 777 heading into the airport.

The 737 was given instructions meant for another aircraft by an air traffic controller in the London control centre, causing it to “climb into confliction” with the 777, a UK Airprox report found.

In evidence given to the inquiry, the 737 pilot said if he and his crew had not selected “altitude hold”, they could have had a “more serious situation”.

Risk of a collision, in his opinion, was of “medium high risk”, and the event was considered an airprox.

An airprox is a situation in which, in the opinion of a pilot or air traffic services personnel, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft involved may have been compromised.

The pilot of the other plane, which was not Europe-registered, did not file a report for the inquiry as he was not required to by UK law.

Nevertheless, the inquiry board was “disappointed” he had not done so, but noted he was operating a foreign-registered aircraft, the report suggests.

A formal assessment of cause and risk found the controller, who was “under pressure” - was also “subject to a high workload” and at the time felt “overloaded”.

Such factors led him to “inadvertently climb” the 737 into conflict with the 777.

The inquiry found that the aircraft which the controller had intended to climb was behind the 737 and was operated by the same company.

Under pressure, the controller had switched their call signs - even though their flight numbers were not similar.

But although the report recognised the controller’s mistake caused the confliction between the planes, he had “taken action” to control the situation.