The IT meltdown that caused travel chaos for more than 75,000 BA passengers at Heathrow and Gatwick Airports a week ago was caused by human error, Willie Walsh, chief executive of BA parent group, IAG has confirmed.

Speaking at an airline conference in Mexico, the former Aer Lingus boss, said an engineer had disconnected a power supply causing a power surge when it was reconnected, that caused IT systems to fail.

He added that the engineer was authorised to be in the data centre where the error occurred, but not authorised to do what he did.

"You could cause a mistake to disconnect the power – it’s difficult for me to understand how you can mistakenly reconnect the power," he continued.

This action "caused physical damage to the servers and distribution panels."

The Irish executive believes that communication problems compounded the damage done by the outage which left 75,000 passengers stranded.

However, he believes the company will bounce back, "It’s damaged us, but it hasn’t destroyed us in any way. We’ve recovered from worse. The BA brand is incredibly resilient," he told the gathering.

BA's outage inspired investor jitters which wiped approximately £500m off the market value of its parent company, IAG.