Passengers at UK airports on Friday faced long delays as Border Force officers walked out in the latest of a string of strikes by public sector workers over pay.
The action follows stoppages this week by nurses and ambulance workers, angered by the government's refusal to increase pay following years of wage stagnation and a cost of living crisis that has seen inflation running at nearly 11 percent.
Around 1,000 workers at six UK airports were taking part in Friday's stoppage organised by the Public and Commercial Services (PCS) -- the first of eight planned between Friday and January 1.
The government has drafted in armed forces personnel and civil servants to operate passport booths at the six airports -- Heathrow, Birmingham, Cardiff, Gatwick, Glasgow and Manchester and the southern coast port of Newhaven.
Travellers, however, were warned to expect delays amid fears that long queues at passport control could lead to people being held on planes, disrupting subsequent departures.
Around a quarter of a million passengers are due to arrive at affected airports on Friday.
PCS general secretary Mark Serwotka said many Border Force employees were struggling with the cost-of-living crisis.
"Forty thousand of our members are using food banks. 45,000 of them are claiming in-work benefits. They are the in-work poor," he told BBC radio, adding that the dispute was also about pensions and job security.
The past year has seen strike action in a range of sectors from dock workers to lawyers as decades-high inflation has eroded earnings.
The government insists it must stick to more modest increases for public sector workers recommended by independent pay review bodies in order to bring inflation under control.
Postal delivery staff belonging to the Communication Workers Union (CWU) meanwhile walked out on Friday for the fifth time this month.
National Highways workers responsible for motorways and major roads in London and southeast England, represented by the PCS, were also on Friday continuing their own four-day walkout which started on Thursday.
Railway workers will stage another strike from 6:00 pm on Friday, Christmas Eve until December 27.
And on Saturday some London bus workers and Environment Agency employees will also launch separate waves of action.
The Border Force strikes will take place every day for the rest of the year, except December 27.