Border Force strikes could go on for six months, a union boss has said, as passport officials walk out on one of the busiest days of the year for airports.
Members of the Public and Commercial Services union (PCS) employed by the Home Office to operate passport booths have begun a strike at Heathrow, Birmingham, Cardiff, Gatwick, Glasgow and Manchester airports, and the port of Newhaven in East Sussex.
The Border Force strikes will take place every day for the rest of the year, except December 27.
Mark Serwotka, the general secretary of the PCS union, predicted a "huge escalation" in industrial action in January across the Civil Service unless ministers enter into negotiations.
"We think that the action at the borders is going to be very effective. We hope that the Government will therefore do the right thing and get around the negotiating table and put some money upfront," he told the BBC Radio 4 Today programme.
"If not, we are raising money, we have a strike fund that means we can sustain this action. Our strike mandate lasts right up until May. We will be supporting this action up to May and we would re-ballot again if we have to.
"It think in January what you will see is a huge escalation of this action in the Civil Service and across the rest of our economy unless the Government get around the negotiating table."
Around a quarter of a million passengers are arriving on flights at affected airports on Friday, including approximately 10,000 people who landed at Heathrow before 7am.
Travellers were warned to expect delays amid fears that long queues at passport control could lead to people being held on planes, disrupting subsequent departures.
But there were no changes to flight schedules as of 7am.
Postal deliveries and driving lessons are also set to be disrupted by strikes in the days before Christmas.
Royal Mail, National Highways and Driver and Vehicle Standards Agency (DVSA) employees are taking industrial action on Friday.
These workers will continue their strike into Saturday, when staff represented by the Rail, Maritime and Transport (RMT) union, Abellio London bus workers and Environment Agency employees will also launch separate waves of action.
This follows two days of strikes by NHS staff, as thousands of nurses walked out on Tuesday, and ambulance workers joined picket lines on Wednesday.
Mr Serwotka urged people affected by Border Force strikes to vent 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."
National Highways workers responsible for motorways and major A-roads in London and the South East, also represented by the PCS, will continue their four-day walkout which started on Thursday.
Postal workers represented by the Communication Workers Union (CWU) walked out for their fifth day of December action, in a move which Royal Mail criticised as "a cynical attempt to hold Christmas to ransom".
The company said it will be doing all it can to deliver Christmas mail, revealing that the industrial action has cost it £100 million.
RMT railway workers will stage another strike from 6pm on Christmas Eve, which could prevent people from making it home for Christmas.
