Eurostar workers were set to walk out for 24 hours this Saturday over working conditions.
RMT members at the St Pancras terminal in central London had returned a 93 percent vote for strikes.
The union says service problems means thousands of passengers are forced onto the crowded concourse during busy periods in summer.
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.”
French Eurostar workers at the Gare du Nord in Paris took action over similar issues earlier this month.