British Airways’ chef executive Alex Cruz has said he is “profusely sorry” to customers as the aviation union claims the IT meltdown could have been avoided.

All of the British flag-carrier’s flights from the two London airports were grounded on Saturday, leaving thousands of customers unable to board.

The problems, attributed to an IT problem, continued over the weekend, with 200 flights in and out of Heathrow cancelled on Sunday and further delays at Gatwick.

BA says the IT glitch was caused by a power outage and ruled out a cyber attack. Alex Cruz said the outage lasted just a few minutes but back-up systems had failed.

Cruz insisted he would not resign amid the fallout from the chaos, but apologised to the 75,000 customers affected by the issues in 170 airports across 70 countries.

Speaking to the BBC, he said: “I am profusely sorry.

“There was a power surge and there was a back-up system, which did not work at that particular point in time. It was restored after a few hours in terms of some hardware changes… we will make sure that it doesn’t happen again.”

Aviation workers’ union the GMB blamed BA’s outsourcing of IT jobs for the systems failure, saying it “could have been avoided”.

In a statement, the union said: “BA’s disastrous computer systems failure is another example of the shortcomings of BA IT systems since they made a number of staff redundant, and outsourced their work in 2016.

Mick Rix, GMB national officer for aviation, said: “This could have all been avoided. BA made hundreds of dedicated and loyal IT staff redundant in 2016 and outsourced the work to India.”

He pointed out that BA has reported “substantial profits” over several years and described the company as “plain greedy”.

Rix said: “We feel genuinely sorry for the tens of thousands of passengers who are stranded at airports and face having their travel plans and holidays ruined.”