The Rome operation, described by Italian media as the largest ever undertaken in the capital region, targeted people who helped lead "illegal activities" in the city and the suburb of Ostia, police spokesman Mario Viola told AFP.
The second, entirely separate operation targeted members of the Ndrangheta in Catanzaro, Calabria, Viola said, adding that 50 arrest warrants were issued for each of the operations.
In Calabria, the arrest warrants concerned "50 to 70 people, including entrepreneurs, politicians and lawyers", Viola said.
In Italy, arrest warrants can be issued against people already detained for other offences.
By early morning, the police were unable to say how many had been detained as part of the raids.
According to the Italian news agency Ansa, around 500 police officers took part in the Rome operation, "the largest ever undertaken" by the police in and around the capital. A helicopter, dog units and maritime police took part in it.