MADRID (Reuters) - Spanish police on Tuesday refloated a submarine that was intercepted with a cargo suspected to be about 3,500 kg (3.85 tons) of cocaine, a security source told Reuters.

Two Ecuador nationals were detained and another person escaped from the vessel in waters off the northwestern region of Galicia at the weekend, the source said. Investigators believe that the crew had attempted to sink the submarine and the drugs it had on board.

Police refloated the vessel with the use of divers and balloons. It was later transported to a port in Cangas, in Pontevedra province.

Once all the drugs are removed from the submarine, investigators will be able to officially determine its composition and weight.

Authorities could neither confirm the origin of the drug nor the intended recipient in Spain, the source said.