Tens of thousands of "angry" civil servants are set to go on strike next month - causing chaos at airports and across the Home Office in a dispute over pay and pensions.
Today the Public and Commercial Services union (PCS) announced that action would begin in mid-December after talks with the Cabinet Office failed to yield an agreement.
Workers at Home Office, Border Force, Department for Transport and Defra previously voted to walkout after being faced with a real-terms pay cut.
PCS general secretary Mark Serwotka said action will start in mid-December and continue for a month - with some workers taking action for the entire month, while others will walk out for shorter periods.
No dates have yet been confirmed, with more industrial action set to be announced next month.
The union says the strikes will affect driving tests and the issuing of driving licences, as well as passport control at airports.
Mr Serwotka said: "PCS members are angry. They helped to keep this country running during the pandemic, and in return, have been treated appallingly by this Government. With inflation now at 11.1%, it is inconceivable that they are expected to cope with yet another real terms pay cut.
"With tens of thousands of members on poverty pay it is no longer about tightening belts, but about choosing between heating and eating - and that is simply not acceptable for the Government's own workforce.
"We have made it clear to the Cabinet Office that we are available for talks throughout this period. I hope that they do the right thing and come back to the table prepared to meet our demands.
"If not, then we are prepared to do what we need to do to show them the value of our members' work once they withdraw their labour."
The PCS is demanding a 10% pay rise as well as improvements to pensions, job security and no cuts to redundancy terms.
The union's National Executive Committee (NEC) today agreed an initial programme of action, which will affect ports, borders and all areas of transport.
It said in a statement: "The NEC will be meeting again to consider further strikes if there are no proposals from the Cabinet Office made soon.
"We currently have a substantial strike fund and have today taken steps to raise significantly more money to support our members striking for a sustained period and carry the campaign on into 2023 if necessary."
Mr Serwotka said: "There could be significant disruption but I hope there isn't any. None of these people want to go on strike but they are suffering in terms of poverty, low pay and cuts to terms and conditions.
"Instead of talking in soundbites, the government should be doing something to stop the workers they employ using foodbanks over Christmas, and they need to remove the threat to tens of thousands of job cuts in the new year."
A Government spokesperson said: "We regret this decision. We greatly value the work of civil servants across the country, but the PCS union's demands would cost an unaffordable £2.4 billion at a time when our focus must be on bringing down inflation to ease the pressure on households across the country, protect the vulnerable and rebuild our economy.
"Discussions will continue but we can provide reassurance that we have comprehensive plans in place to keep essential services running and to minimise disruption if these PCS strikes do go ahead."
The Government said the headline range for civil service pay awards is up to 3%, with departments able to make average pay awards up to 2%.