Italian police seized a record 5.3 tons of cocaine during an operation off the southern coast of Sicily, authorities said on Friday.

The haul had an estimated value of €850 million ($946 million) and is the largest cocaine seizure ever reported on Italian territory.

Five people have been arrested, the Guardia di Finanza said in a statement.

How were the drugs discovered? 

A merchant ship sailing from South America had already been under observation for several days, when a surveillance aircraft spotted packages being thrown from its deck into the waters of the Strait of Sicily to be collected by a fishing trawler.

In the early hours of Wednesday morning, investigators noticed numerous parcels being thrown into the water from the merchant vessel as a fishing boat approached. The crew of the smaller boat then retrieved the parcels.

The investigators stopped the trawler and found large quantities of drugs in a hidden compartment on the vessel. Two Tunisians, an Italian, an Albanian and a French national were arrested.

Sicilian regional president Renato Schifani called the operation a blow against drug smuggling.

"Drugs are a scourge of our society fueled by unscrupulous men who sow death by crushing hopes and destroying many families," he said in a statement.

los/wmr (dpa, Reuters)