In a tweet, Heathrow Airport said: ‘We are experiencing technical issues at the airport which we are working hard to resolve.
‘To help direct customers to their gates, we have deployed additional Heathrow colleagues across our terminals.
Jenny Nielsen tweeted pictures of whiteboards displaying handwritten flight numbers and destinations.
British Airways told a customer on Twitter: ‘We’re aware Heathrow Airport is currently experiencing a technical issue that is impacting some of their IT systems across the airport, affecting a number of airlines.
‘We are working with them to resolve the issue as a priority and apologise for the delay to our customers.’