French police say they have received a record haul of nitrous oxide, more commonly known as laughing gas.
Seven tonnes of the gas were recovered from a warehouse in December near Paris, police said on Twitter.
The nitrous oxide was found in cylinders in the suburb of Noisiel and has a street value of €2.75 million, they added. Three people have also been arrested as part of the operation.
The discovery was made after an investigation was launched by French authorities in Lyon in September.
Police say the probe focused on an organised criminal gang that was selling and distributing nitrous oxide on the black market.
Laughing gas is popular among partygoers and young people in France for its euphoric effect, but the gas can cause asphyxiation, loss of consciousness, or even severe neurological and cardiac disorders.
Since 1 June last year, France has banned the sale of nitrous oxide "to obtain psychoactive effects" with a fine of €3,750.