Officers in the southern city of Lecce, and in Bologna and Ravenna in the north acted together to break up the operation, arresting nationals from Afghanistan, India and Pakistan.
Police began investigating in 2010 after they found about 50 migrants from Afghanistan, including some children, hidden on a boat docked in Ravenna, Commissioner Elena Joland Ceria of Bologna police told Sky TG24.
They were crammed into chemical toilets hidden inside a lorry on board the vessel.
Police discovered that the traffickers brought the migrants in on small boats that were in poor condition or hidden in ferries serving ports on the Adriatic coast.
Given the conditions, they were in constant danger of death, said investigators.
Once in Italy, they were moved on towards Germany, Switzerland, Austria, France, Belgium and Denmark.
Investigators think the operation was run from Greece and Turkey.
It had cells operating in the capital Rome; in the northern cities of Milan, Cremona, Bologna, Bergamo and Brescia; in the central cities of Teramo and Ascoli; and Bari in the south.
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