Eurostar station staff based at London’s St Pancras are to go on strike on Saturday, claiming they face “shocking and dangerous” working conditions because of repeated service failures and breakdowns.

Members of the Rail, Maritime and Transport (RMT) union will walk out for 24 hours after talks broke down without agreement.

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.

“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.

“Our plan is to run a normal service so that all passengers booked to travel with Eurostar will be able to do so.”