A Eurostar passenger reportedly sparked a bomb scare at a French station after trying to board the train to London with a "military relic".
The cross-border operator said Gare du Nord station in Paris was evacuated after a "suspect package" was discovered on Saturday afternoon.
Witnesses reported scenes of confusion at the transport hub, with several saying on social media that they heard a controlled explosion.
One person wrote on Twitter: "No information on what's going on at gare du Nord!?! Massive queues, delays , explosion... Any update for your passengers?"
Eurostar replied to another person online, writing: "Somebody tried to take through a military relic so it's just being checked and check in should be open very shortly."
The high-speed service provider reassured passengers that services had not been cancelled but "interrupted until further notice".
One tweet read: "Check-in was interrupted due to the presence of a suspect package which caused the evacuation. We're sorry for the inconvenience."
Businessman Martin Adams was on his way to get the 4.13pm service to London when police cordoned off half of the station.
The 31-year-old, who had been returning from a weekend in the French capital with friends, told the Press Association: "The police told us that there would be a controlled explosion and about 10 minutes later there was, nobody panicked and everybody just got about lining up for their trains.
"A lot of people missed the 4.13pm as a result but Eurostar placed people on later trains.
"My wife heard someone say in the security line that it was a tourist trying to bring a part of an old WWII bomb back through customs.
"This wasn't confirmed to us by Eurostar or security who just referred to 'security issues' when announcing delays."