A mistake by a UK air traffic controller put a passenger plane on a collision course with another aircraft, an official near-miss report has said.

The controller thought an Airbus A319 leaving Luton Airport was on one departure routing when it was on a different one.

When the A319 was given an instruction to climb to 5,000ft it "brought the aircraft into confliction" with another A319 which was on a positioning flight from Stansted to Luton with no passengers aboard.

Describing the incident which took place three miles from Luton Airport on September 12 last year, the UK Airprox (aircraft proximity) Board said that when the controller "realised his mistake" he gave avoiding-action instructions to both aircraft.

The minimum separation between the two planes was 3.5 nautical miles (just over four miles) horizontally and 100ft vertically.

As is usual in such reports, the board did not give details of which airlines were involved.