President Juan Manuel Santos on Wednesday announced Colombia’s police had seized 12 tons of cocaine, which he said was the largest single drug seizure in the history of the country.

The drugs were discovered stored underground when around 400 anti-narcotics police stormed four farms in a banana-growing area in the northwestern department of Antioquia.

"Never before, since we began more than 40 years ago to fight against drug trafficking, have we made a seizure of this magnitude," Santos told reporters.

Santos said the seizure meant that police hauls of drugs in the year to date, 362 tons, had already surpassed the 317 tons seized in 2016.

Police estimated the value of the haul at around $360 million.

They said the drugs belonged to Colombia’s most-wanted man, Dario Antonio Usuga, alias "Otoniel", who is the chief of the country’s largest drug-trafficking gang, the Gulf Clan.

The Gulf Clan emerged from the remnants of right-wing paramilitary groups that demobilized in 2006.