An international police operation has seized 5.2 metric tons (5.73 short tons) of cocaine with a street value estimated at around 200 million euros ($232 million) on a yacht in the Atlantic Ocean, writes ABCNEWS.

Portuguese police said the shipment was one of the largest hauls in Europe in recent years and the biggest in Portugal for 15 years.

Police backed by Portuguese navy and air force units located and intercepted a 24-meter (79-foot) yacht at sea, a statement said. They boarded it and found 183 bales of cocaine on board.

Police suspect the cocaine belonged to an international drug-trafficking gang that was bringing cocaine into Europe through the Iberian Peninsula.

Three men were arrested and taken to Portugal.

The operation involved police from Portugal, Spain, the U.S. Drug Enforcement Administration and the United Kingdom’s National Crime Agency.

Authorities said they would release further details of the operation later Monday.