Spanish police said Thursday they had seized over four tonnes of cocaine from a boat off the Canary Islands in the Atlantic and arrested its four crew members.
The semi-rigid speedboat carrying cocaine from South America was spotted some 500 nautical miles (920 kilometres) south of the Spanish archipelago, which lies off the northwest coast of Africa.
The operation was carried out in cooperation with Britain's National Crime Agency and the US Drug Enforcement Agency, police and Spain's customs authority said in a joint statement.
The police said the boat was unlikely to have operated alone.
"This type of vessel, when used in the Atlantic, requires regular assistance to be supplied with water and food as well as fuel, supplies that are delivered by other sporting, fishing or semi-rigid boats of the same type," the statement said.
"The operation remains open and the possible presence in the area of other vessels that could be involved is being investigated, so new operations can't be ruled out."
The four arrested crew members were from Romania, Spain, Moldova and Morocco.
Spain is one of the main entry points for drugs into Europe given its close ties with Latin America, which is the main source of cocaine, and its proximity to Morocco, a key source of cannabis resin.
On Friday night, two police were killed when their patrol boat was rammed by a speedboat driven by drug traffickers off the southern port of Barbate, 70 kilometres (40 miles) west of Algeciras.
Eight people were arrested over that incident, which also left another two police injured.