British Airways has apologised to passengers following a technical glitch that caused severe issues on Sunday at Heathrow and Gatwick airports. 

The airline is in the process of upgrading its check-in system, but something went wrong yesterday, one of the busiest days of the year, causing severe delays. 

Check in system down at @HeathrowAirport terminal 5 ... This is fun 😣😣

— Phillip Schofield (@Schofe) July 17, 2016

TV presenter Phillip Schofield was one of the many passengers who missed their flight as a result of the glitch.

 

You asked for pictures @british_airways .. Here's mine, plane leaves in half an hour, been in the queue for 2 hours and not one member of staff to talk to. Love you usually, today you are s***

A photo posted by Phillip Schofield (@schofe) on Jul 17, 2016 at 7:48am PDT

BA says the problems have been resolved and flights are operating normally. They apologised for the delays and said it had extra staff in place to help customers. 

A spokesman for the airline added: "Our IT teams worked very hard to quickly fix a short-lived problem with our check-in system.