Initial reports did not state where the 48 suspects were arrested, their nationalities or the charges they face.
Police from several regions of Italy were involved in the probe of the gang, which was allegedly linked to a Kurdish international people smuggling organisation with operations in Asia and Europe.
The alleged organisation forged passports and identity documents for illegal migrants and had operations in Afghanistan, Pakistan, Iran, Turkey, Greece, France, Sweden, Norway and Britain, according to investigators.
Would-be illegal immigrants' relatives paid "large sums" of money to the people smugglers for their passage and upkeep, investigators said.
The money was transferred via informal banking channels, such as the 'hawala', or money brokers which are popular in the Islamic world, leaving no electronic trace of the transactions, according to investigators.
The money brokers used in the people smuggling racket were located mainly in the Middle East, North Africa, the Horn of Africa and in India and Pakistan, investigators said.
Police from the Italian capital, from the northern city of Bolzano and from the southern city of Foggia were involved in the investigation, as was the Rome police headquarters' immigration office.