Italy's interior minister says police and prosecutors have cracked a transnational network dedicated to migrant trafficking.

Palermo-based authorities have detained 38 people suspected of being in the ring: 25 Eritreans, 12 Ethiopians and one Italian.

Interior Minister Angelino Alfano says the authorities dealt "a harsh blow" to the criminal network, which used Rome for its financial transactions hub.

Palermo police say in a statement that an Eritrean man who was arrested in 2014 collaborated with authorities, providing for the first time "a complete reconstruction of criminal activities" of migrant trafficking involving operations both in North Africa and Italy.