Passengers are being warned to brace for Christmas travel chaos on Friday as a Border Force strike begins.

Around 1,000 members of the PCS union who staff passport booths will walk out, bringing disruption to major airports such as Gatwick and Heathrow.

The action is expected to bring delays to around 250,000 incoming passengers at the busiest Christmastime for airports since 2019.

Heathrow - the UK’s busiest airport, where some 579 flights are due to land on Friday - could be the worst affected.

Around 10,000 passengers are due to arrive before 7am alone, with the first flight - a British Airways service from Cape Town - due to land at 4.45am.

Birmingham, Cardiff, Gatwick, Glasgow and Manchester airports, as well as the port of Newhaven are also affected. Picket lines will be mounted outside.

Delays in checking the passports of arriving passengers could lead to long queues and even people being held on planes, delaying departures.

Border Force head of operations Steve Dann earlier conceded that military personnel and civil service volunteers will not be enough to limit the disruption.

He said that while “robust plans” were in place, “contingency workforce will not be able to operate with the same efficiency as our permanent workforce".

Electronic passport gates will remain open but they cannot be used by all passengers, such as children aged under 12.

Industrial action by National Highways staff will also continue Friday, while the country’s rail network is set to come to a complete standstill on Christmas Eve due to strikes.

The Border Force strikes will continue from December 23 until New Year’s Eve with the exception of December 27.

Around two million passengers are estimated to be booked to fly into the affected airports during the walkouts.

It comes amid a long-running dispute with the Home Office over pay, pensions and conditions.

PCS general secretary Mark Serwotka told people affected by disruption to direct their anger at the Government.

"The Government could stop these strikes tomorrow if it puts more money on the table," he said. “Like so many workers, Border Force employees are struggling with the cost of living crisis. They are desperate."

Paul Charles, chief executive of travel consultancy The PC Agency, said: "It’s the uncertainty that is worrying passengers, as they have no idea how the strikes will impact their arrival experience.

"Many are likely to face longer queues and delays during this festive period, and some could find themselves stuck on arriving aircraft before being allowed into the terminals.

"Let’s hope that border officials can process all passengers smoothly and without worry."