The men, aged between 20 and 30, used a thread from a blanket and a small needle to sew their mouths shut at the Ponte Galeria facility yesterday. They are receiving medical care, ANSA said.
One of the four was due to be repatriated to his home country tomorrow.
The heavily guarded Ponte Galeria immigrant detention centre, located near Rome's Fiumicino airport to facilitate deportations, houses around a hundred illegal migrants.
How to deal with the growing number of immigrants is a controversial issue in Italy.
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More than 33,000 migrants had landed in Italy as of late October - nearly three times more than the number for 2012. Most come from impoverished African countries but now also from Syria.
The latest incident comes just days after Brussels condemned the "appalling" conditions at some of the country's migrant centres, following the release of footage of naked asylum-seekers being hosed down at a facility on the island of Lampedusa.