Eurostar station staff based at London's St Pancras have announced they will go on strike over the "shocking and dangerous" working conditions they face due to repeated service failures and breakdowns.
Members of the Rail, Maritime and Transport (RMT) union will walk out for 24 hours on July 28.
The union claimed the international terminal at St Pancras has been reduced to "chaos", with staff bearing the brunt of public anger over delays to services.
Around 140 staff are involved in the dispute.
RMT general secretary Mick Cash said: "The conditions at St Pancras have been simply appalling in recent weeks, with dangerous levels of overcrowding on the concourse as services plunge into meltdown on the cusp of the busiest part of the year.
Yep, our train is now late and no time set for boarding. Electrical troubles at the tunnel. I guess we will be filing a compensation claim. Hopefully we will make our @LaTourEiffel tour that is booked for today. @Eurostar #EuroStar #eiffeltower pic.twitter.com/OosXPtPaPG— RobertReddHistorian (@SEVHistory) June 24, 2018
"RMT will not tolerate a position where our members are left to pick up the pieces due to corporate failures."
The union said it was escalating the dispute by balloting train managers for industrial action over the same issue.
A Eurostar spokesman said: "We are aware of the proposed strike and are disappointed that this action is planned.
"We are keen to find a solution and have a meeting scheduled with the RMT to discuss this further.
"If the strike action goes ahead, our plan is to run a normal service so that all passengers booked to travel with Eurostar will be able to do so."
Additional reporting by Press Association