Bolivian police have seized more than 7.2 tons of cocaine that was found hidden in scrap metal headed for a port in neighboring Chile for export to Europe, the nation’s Interior Minister announced Monday. Interior Minister Eduardo del Castillo said at the Monday press conference that it was the second-largest drug bust in the country’s history, and would deprive drug traffickers of more than $451 million.

The drugs were discovered at a customs checkpoint in the Pisiga region, on Bolivia’s border with Chile, hidden in trucks that were carrying container loads of scrap metal for export to Belgium, which has become a main gateway for Latin American cocaine cartels into Europe.

“Upon reviewing the merchandise, which was inside the vehicles, it was determined that the load of two containers was contaminated with controlled substances,” del Castillo said Monday.  “Police officers realized that the merchandise had unusual characteristics and proceeded to drill it to discover cocaine.”

“If we take into account the price of these controlled substances in the country of destination, we’re talking about an impact on drug trafficking of more than $451 million,” he said at the outdoor news conference, as heavily armed forces guarded both the seized drugs and three men who were arrested in connection with the bust.

Del Castillo said the individual believed to be behind the thwarted drug sale had fled Bolivia to the U.S., which he blamed on a leak from the federal prosecutor’s office to media outlets.

Bolivia’s biggest-ever drug bust came only weeks ago, when police seized close to 9 tons of cocaine in January in an operation that also took place on the border with Chile.

The United Nations Office on Drugs and Crime says Bolivia is the third-largest grower of coca, the plant from which cocaine is produced, in the world. In a March report, UNODOC said there had been a rise in shipments of cocaine from southern parts of South America, including Chile, to Europe.