Passengers are being warned that strikes will ground flights and bring chaos to UK airports over the busy Christmas period.
Travellers were urged to rethink plans for flying by Home Secretary Suella Braverman who warned of “undeniable, serious disruption” if the strikes go ahead.
Up to 30 per cent of flights could reportedly be hit by striking border control workers at airports including Heathrow, Gatwick, Manchester and Birmingham.
The “entire travel support system will once more be plunged into dealing with cancellations and disruptions”, the Business Travel Association (BTA) said.
Border Force workers at several British airports will go on strike for eight days in December in a dispute over pay, threatening disruption at one of the busiest times of the year.
Ms Braverman said the planned strikes threatened severe delays.
“It's very regrettable that they have made this decision to potentially strike over critical times in the run-up to and following Christmas and the New Year,” Ms Braverman said.
“If they go ahead with those strikes there will be undeniable, serious disruption caused to many thousands of people who have holiday plans.
“I really want to urge people who have got plans to travel abroad to think carefully about their plans because they may well be impacted.
“We've got plans in place that will involve, to a degree, bringing in some of our military colleagues to help us in a variety of roles.
“Ultimately I'm not willing to compromise on security at the border, that's the number one priority.
“That may well have an adverse impact on convenience for people, frankly, whether it's the time they have to wait for flights, or departures, they may well be delayed on arrivals and various travel plans. Ultimately security at the border is my number one non-negotiable priority.”
The Public and Commercial Services union (PCS) said up to 3,000 staff employed by the Home Office would be involved in the walkouts on all but one day between December 23 and 31.
The BBC reported aviation experts estimated it would be possible to operate about 80 per cent of flights. The Times newspaper reported that up to 30 per cent of flights could be cancelled on strike days.
Heathrow and other airports said they are working with the airlines and Border Force to mitigate disruption.
A representative at the BTA said: “Further strike action puts British workers' Christmases at risk. Hard workers up and down the country will be stranded, struggling to get home.
“The entire travel support system will once more be plunged into dealing with cancellations and disruptions, rather than bookings, with no financial recompense.
“We urge the government and unions to come together to ensure there aren't unnecessary empty chairs at this year's Christmas table.”
Gatwick Airport said there will be additional staff around on strike days “to help with passenger welfare”.
“We are disappointed that Border Force staff have decided to take strike action at this particular time. We hope that a settlement to this dispute can be found as quickly as possible,” a representative said.
“We expect that flights will operate as normal and remain in regular contact with Border Force about their mitigation plans. Additional airport staff will also be made available to help with passenger welfare on strike days.”
A Heathrow representative said: “Our priority is to ensure passengers get through the border safely and as quickly as possible.
“We are working closely with airlines and Border Force on mitigation plans for potential strike action by Border Force officers and these plans will now be implemented for the notified days.”
PCS general secretary Mark Serwotka said the passport control staff will take part in the strike with a “significant impact” expected.
He warned the government against bringing in the military to cover for the strikes, saying there was not enough time to train them properly.
Mr Serwotka has met ministers but he said they were refusing to increase a 2 per cent pay rise.
A spokesman for Airlines UK, which represents the industry, said: “We urge all parties to work on reaching an agreement to avoid the need for industrial action at what is such an important time of year for many travellers.”
