Italian police found more than 20 tonnes of hashish with an estimated street value of 200 million euros ($230 million) hidden in the hull of a cargo ship, a statement said on Friday (Oct 16).

Acting on a tip, finance police -- who help oversee border security -- boarded the ship at sea and diverted it to the port of Cagliari in Sardinia, where they spent more than 18 days searching before finally finding the drugs, according to a statement.

During the search, police used cranes to move enormous blocks of granite carried by the cargo ship Jupiter, which is registered in the Cook Islands.

They eventually found 821 packages of hashish weighing a total of 20.5 tonnes in a ballast tank in the bow of the ship.

The ship’s captain and nine crew members, all Syrian, were arrested, the statement said. No further details about the seizure were provided. The ship’s last port of call was Vigo in Spain.

Italy’s finance police were aided by the Guardia Civil in Spain and Europol, as well as French and Portuguese authorities, the statement said.