British Airways flights in Britain were being delayed and passengers were suffering long waits at airports on Saturday because of a global system outage, the airline said.
"We apologise to customers who are facing some delays following an IT outage this morning," a BA spokeswoman said.
"We are working to resolve the problem as quickly as possible."
She gave no further details.
Passengers on social media reported long delays and flights by the IAG-owned airline being held on runways, at the start of a long holiday weekend in Britain.
"Still on the tarmac at Leeds. #britishairways reckon Heathrow is so backed up we can't set off. No way we'll make our Vegas flight," one passenger David Raine wrote on Twitter. 
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