Police in southern Italy and Germany have arrested 13 people, most of them Somalis, accused of transporting migrants who had arrived in Italy by sea to locations throughout Europe.

The arrests Wednesday, coordinated by anti-mafia prosecutors in Salerno, follow several similar investigations into the land-based trafficking networks that have sprung up amid Europe's migrant crisis.

Eurojust, the EU's judicial cooperation agency, said the investigation began in 2015 after 545 Somali migrants were rescued at sea and brought to Salerno. Telephone intercepts indicated they had contacts with Europe-based traffickers who could get them to their ultimate destinations in Germany, Austria, Sweden, Belgium and the Netherlands.

The alleged ring-leader was a German citizen of Somali origin who was picked up in Germany, Eurojust said.

The suspects are also accused of harassment and inhuman treatment since some migrants had scabies.