Passengers arriving at Heathrow are being delayed for several hours due to a problem with self-service passport gates.
Some travellers at Terminal 5 posted images of long queues on social media on Wednesday morning, while others were being held on planes due to the congestion.
George Zarkadakis, an artificial intelligence engineer, wrote on Twitter: “System for scanning passports is down (again). Expected time of waiting for arriving passengers: 2-4 hours.
“I think I’ll stay home next time… and stick to Zoom calls.”
Another passenger, Thomas de Lucy, tweeted: “Not only are we waiting for two hours at passport control but Heathrow staff are all incredibly rude, shouting at people and ignoring others.
It is less than a fortnight since a widespread e-gate failure caused delays at airports across the UK.
E-gates – managed by Border Force – allow travellers with biometric passports to pass through border control without a manual inspection.
Heathrow wrote on Twitter: “We’re aware of an issue impacting the e-gates, which are staffed and operated by Border Force.
“We apologise for the impact this is having on your journey.
“Our teams are working closely with Border Force to resolve this as quickly as possible.”