The smugglers were making almost daily trips to Spain, taking around 10 minutes to cover the 18-kilometre (11 miles) crossing, said a police statement.

Landing on beaches in the Cadiz or Malaga regions in southern Andalusia, the migrants were then driven to Algeciras. There, they would be held until their relatives on Ceuta, the Spanish territory on Morocco’s northern coast, had paid their debt.

Police arrested one of the smugglers at Algeciras, another two in Ceuta and said two more were on the run and subject to international arrest warrant.

On Wednesday, Spanish coastguards rescued nearly 600 people from 15 boats and recovered a jet ski in the waters between Morocco and Spain, a route increasingly used by migrants.

Among them, there were at least 35 children and a baby.

According to the latest figures from the International Organization for Migration (IOM), 8,385 migrants had arrived in Spain this year by August 9.

But at least 121 had drowned trying to make the same crossing.

At this rate, the IOM has noted, Spain could overtake Greece as the main route for migrants attempting the Mediterranean crossing.

The smugglers use small crafts to make the crossing in an effort to slip past Spanish police and coastguard.