Security staff on the Eurostar are to go on strike next month.
Members of the Rail, Maritime and Transport (RMT) union will walk out on 16, 18, 22 and 23 December in a dispute over pay.
The strike will "severely affect" Eurostar services for travellers close to Christmas, the union said.
The workers, some of whom earn £10.66 an hour, rejected a below inflation pay offer and voted overwhelmingly for strike action.
More than 100 staff are expected to take part in the action.
Responding to the announcement Eurostar said: "We are aware that negotiations between Mitie and the Unions are ongoing. If there is any impact on services we will update customers as soon as possible."
Mick Lynch, general secretary of the union, said: "Eurostar security staff are essential to the running of Eurostar, and it is disgraceful they are not being paid a decent wage."
He said they work "long, unsocial hours" and that facilities management firm Mitie "can easily afford to pay them decently".
"We do not want to disrupt people's travel plans, but our members need a pay rise, and this is the only way management will listen," he said.
He called on Mitie and Eurostar to come to a negotiated settlement with RMT as soon as possible.
Mitie said they're disappointed with the action and have already offered a pay increase with negotiations ongoing.
"In addition, we recently announced a £10m winter support package, designed to help the lowest paid colleagues across Mitie with the rising cost of living.
"As always, our priority is to ensure that exceptional services are delivered as normal so that passengers are able to continue their journeys with minimal disruption."
The industrial action will coincide with other railway strikes - with RMT members at Network Rail and 14 train operators planning walkouts on 16 December.
Walkouts by train and railway station cleaners are due to take place on 22 and 23 December.
It comes amid strike action by Royal Mail workers, university lecturers and sixth-form college staff today over pay, while the army is on stand by in case it is needed to fill roles during strikes by NHS workers over the winter.
Nurses will take industrial action on 15 and 20 December across England, Wales, and Northern Ireland over pay and patient safety.
The strike ballot among more than 300,000 members of the Royal College of Nursing (RCN) was the biggest in the union's 106-year history.
Thousands of 999 call handlers, ambulance technicians, paramedics and their colleagues working for ambulance services in the North East, North West, London, Yorkshire and the South West are also due to go on strike next month over pay and staffing levels.