Some €30 million ($35 million) worth of cocaine has been confiscated from a container in the northern French port city of Le Havre.
Customs impounded 752 kilograms of the narcotic on Friday, which had arrived on a ship from South America.
France 3 TV Normandy cited a customs source as saying the discovery was made during a routine check of containers from abroad.
The Agence France-Presse news agency said no arrests have been made yet.
French Budget Minister Gerald Darmanin praised customs officials for their "exceptional" haul.
Customs at Le Havre seized 3.5 tons (3,175 kilograms) of cocaine last year, according to an annual police report on trafficking.
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Record year for trafficking
The same figures revealed a new record level of cocaine smuggling to France in 2017 of 17 tons, compared with 8.5 tons a year earlier.
Production of the drug from South America is increasingly flooding the European market, France's Europe 1 radio reported, adding that Colombian drug cartels, in particular, have quadrupled production.
"Production over the past five years has increased significantly in Latin America," Vincent Le Beguec, the head of the French Office of Narcotics, told the broadcaster.
Read more: Cocaine 'resurgence' in EU as South America output rises: watchdog
Much of the 2,000 tons of global cocaine production will find its way to Europe, the radio station added.
French authorities estimate that the drug sells in France for up to 65 times its original purchase price.
mm/jm (AFP, dpa)
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