French authorities announced a large seizure of the party drug MDNA this week, but were later forced to admit it was no illegal narcotic.

The Paris police headquarters on Wednesday hailed a "fruitful investigation" on Twitter, showing what they said was a narcotics workshop. The site was allegedly used to package the drug ecstasy before supplying it to illegal parties.

Investigators claimed to have seized 25 kilograms of the drug, with a street value of €1 million ($1.2 million).

The accompanying images showed a powdered pink substance and packets of pink pills.

Two men detained

Police raided an apartment in Saint-Ouen, a suburb just north of Paris, and two men were arrested in connection with the haul, according to France Bleu radio.

They were also held in connection with the theft of 200 smartphones.

However, toxicological tests carried out on Thursday concluded that the substance was just a "neutral powder."

The local prosecutor's office told the AFP news agency that it was "not related to narcotics or poisonous substances."

Instead, the suspicious substance was "crushed Tagada strawberry" sweets, of the kind produced by Germany's Haribo, according to a source close to the inquiry.