Two Eurostar trains bound for London were delayed and a station evacuated after a "World War souvenir" was discovered.
Police were called to Paris Gare du Nord station after the find, which was reported to be a shell, was made on Sunday morning.
The check-in area at the transport hub was evacuated as a precaution, a spokeswoman for Eurostar said.
The Paris to London service at 08.13am (07.13 GMT) was delayed by 20 minutes, while the 09.13 (08.13 GMT) was held back for half an hour.
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