Spanish police working in cooperation with the U.S. Drug Enforcement Agency say they have arrested six members of a Colombian-based drug-trafficking gang and seized 240 kilograms (530 pounds) of cocaine that had been hidden inside a yacht.

According to Saturday's police statement, their investigation opened in April after police learned that a Spanish citizen based in Colombia was smuggling cocaine into Europe by sea.

Police say they raided three premises after the gang leader, his wife and four gang members from Colombia traveled to Spain as part of their latest cocaine-smuggling operation. The gang leader and his wife were arrested in Madrid, the four henchmen in the southwest province of Huelva.

The drugs were found concealed within the hull of the yacht at the Huelva port of El Rompido.