Updated: Facial recognition scanners at Manchester Airport have been switched off after an incident in which the robot guard let a couple through the gate even though they had swapped passports.

An immigration officer stopped the couple after they got through the barrier.

The UK Border Agency told the Beeb: "Following the incident, the gates at Manchester are suspended and we are reviewing the circumstances of this incident." The scanners are meant to compare your face with the image stored on the chip of a biometric passport.

The UK Border Agency project to test scanners at Manchester was criticised by chief inspector John Vine in December for failing to properly evaluate the supposed trial.

John Vine, the independent chief inspector, said: "Increasingly, the UK Border Agency relies upon technology, such as facial recognition gates, to increase security and make better use of its staff.

"During this inspection, I found that this new technology was not operational for a significant period of time. As a result, I recommend that the UK Border Agency gives priority to evaluating the actual benefits intended by such technology."

Vine found gates broken at the airport five times in a week – four out of five times the damage was technical and one had broken down due to a lack of staff responsible for repairing the device. UKBA told Vine that maintenance of the machines was the responsibility of a company based in Portugal and machines were meant to be fixed within four working days.

There were suggestions early in the project's life that the machines' software had been re-calibrated because they were making too many false negatives – flagging up too many people for not matching their documents.

Updated:

Brodie Clark, Head of Border Force, UK Border Agency said: “There was no breach of security or immigration control. E-Gates are used in conjunction with manual checking by border officials and in this case both individuals were stopped by the Immigration Officer responsible for supervising the gates.

"The E-gates were temporarily suspended whilst an investigation was carried out. The investigation concluded that no other sites were affected, and the border was not compromised as a result of the incident.

"The gates have now re-opened and we will continue to monitor their performance to ensure they operate safely and securely. To date more than 3 million people have used the E-Gates system."®