Mujhait Muhammad would brace himself as evening fell, when the five smugglers manning the boat bound for Europe would begin beating him and the other migrants with hammers.

Each one of them was bound by rope. The smugglers repeatedly struck their heads, arms and legs to handicap their human cargo. On one occasion, a smuggler smashed someone’s eye with a hammer, then plunged his fingers into the socket.

Each night, more people died; each morning, the smugglers heaved their corpses into the water. They had been promised safe passage from Mauritania to Spain.

“We feared every day that our time had come, that we would be the next ones dead in the ocean,” said Mr Muhammad, a 29-year-old Pakistani farmer, one of 22 survivors out of the 80 migrants crammed on the boat earlier this month.

“I kept thinking about what would happen to my family – my baby daughters, my wife, my parents – if I died.”