International travellers arriving at UK airports have been warned of long delays as Border Force staff who check passports begin a series of strikes over better pay and working conditions on Friday.

More than 1,000 employees have walked out, affecting passport control desks at Heathrow, Gatwick, Birmingham, Cardiff, Manchester, and Glasgow airports, as well as the port of Newhaven in East Sussex.

The strike will last until early on Monday, before another round of strike action from December 28 until early on December 31.

Military personnel and volunteers will be standing in for the striking workers and the UK Home Office, which is responsible for the Border Force, has drafted in officials from other departments as a contingency workforce.

More than 10,000 flights are scheduled to land at those airports during those times and around 250,000 passengers arriving on Friday are expected to face delays.

The affected airports have indicated that most departing flights should not be affected, with only some arriving passengers – particularly those who cannot use e-Gates – facing delays.

Meanwhile, Royal Mail postal employees will also be on strike on Friday, their fifth day of industrial action this month.

It has been estimated that the strike, which will continue on Saturday, has already cost Royal Mail around GBP 100 million.

National Highways workers in London and the south east of England will continue their four-day walkout that started on Thursday.

It marks part of what has been dubbed a winter of discontent as workers across different sectors are taking industrial action as their unions seek pay rises in line with the rate of inflation to help cope with an ongoing cost-of-living crisis.

Rail workers represented by the RMT union will begin strike from Saturday evening until December 27 with a few other services also impacted.

Driver and Vehicle Standards Agency employees will strike on Friday and Saturday in northwest England, and Yorkshire and the Humber, with more strike action expected in other regions over coming weeks.

Many bus drivers in south and west London are planning a strike on Saturday and two further days this month, before a further eight days in January in their pay dispute.

Earlier this week, state-funded National Health Service (NHS) staff were on strike, with nurses walking out on Tuesday and ambulance workers following them on Wednesday.

The government has refused to negotiate on pay with public sector workers, insisting it is accepting recommendations from independent pay review bodies and pay rises would make the inflation crisis worse.