British Airways' computer systems went down globally on Saturday, leading to widespread delays and even cancellation of flights from Heathrow and Gatwick for hours, media reported. The carrier apologised for the “current IT systems outage”. “We are working to resolve the problem as quickly as possible,” it said in a tweet. Heathrow Airport said it was “working closely” with BA to resolve the issue. There is no evidence at this stage to suggest the system failure was caused by a cyber attack, British Airways told BBC. The IT system failure came as many Britons headed overseas for the long weekend and half-term school holidays. British Airways' website was unavailable and some travellers claimed they could not check in on the mobile app.