The man believed to be the "top boss" of an alleged Italian crime family is among those arrested in a police sweep.
At least 300 people were arrested on Tuesday on suspicion of crimes including murder, money laundering and belonging to a criminal organisation.
The Calabrian mafia, known as 'Ndrangheta, is one of Italy's major criminal organisations.
Domenico Oppedisano, 80, said by police to be the family head, was arrested a small coastal town in Calabria.
Police also arrested the organisation's manager in Milan, northern Italy, among 160 others in the Lombardy region.
Those held include businessmen and a public health official.
The operation also involved arrests in the US, according to reports.
The sweep comes after the northern branch of the family tried and failed to secede from the southern part of the operation, sparking a mafia war, the news agency Agence France Presse reported.
Analysts say the group had expanded out of its Calabrian heartland to play a major role in organised crime throughout Europe, and in the international drugs trade from South America.
The police have also seized assets worth millions of euros.
The police operation involved 3,000 officers and is the largest carried out by police in recent years, local media said.
Anti-mafia prosecutors say that the operation exposed crucial information about how the family operates, and made extensive use of wiretaps.
BBC Online readers have been sending us their on this story. Here is a selection of their comments.
I left Calabria as a very young man. I could never understand how this cancer was allowed to thrive by a succession of Italian governments. As a more mature man I realise that it, like cancer, is very difficult to defeat. Yet, progress is being made - slowly but inexorably, I hope.
Frank, Huntington, New York, US
Today is a great day for all of us Calabresi. This important blitz opens the mind of the world to the criminal power of our cancer called 'Ndrangheta. The Godfather image belongs to the past: today organised crime lies in economical and political institutions. International broadcasters must help us by informing people. I'm a journalist here and for us it's very hard work without support. Dozens of us, in the last months, have been intimidated with bullets and cars burnt and so on.
Fabio Melia, Reggio Calabria, Italy
I'm a Calabrese in New York and I'm sick to death of these types of arrests both in Italy and America. The cops, FBI and the Italian Carabinieri should be going after the terrorists, not some 80-year-old grandfather who is no threat to society.
Anthony Bensonhurst, New York, US
I suppose that these arrests are only the tip of the iceberg of this new direction in 'Ndrangheta strategy. They're now installing themselves where the power is stronger. Milan and the surrounding region is the preferred location for these people to make business thanks to growing financial speculation.
Domenico, Bari, Italy
My hope is that this disease that affects my country will soon be eradicated. Unlike them, I have the honour to be an honest worker and I appreciate and commend the state action in the fight against crime in all its forms.
Gianfrancesco, Cosenza, Italy
This is a minor set back for the mafia. There have been a number of maxi-arrests recently. It may sound exciting and effective but life here continues as normal, when someone is arrested, there is always somebody new to take their place. The mafia are in complete control, this is the culture in the south of Italy. Occasional headlines may allow a few politicians their personal success, but everybody knows who is really pulling the strings.
Anonymous Brit, Reggio Calabria, Italy
I am scandalised that at this day and age the mafia still persists in Italy however I hope these arrests will be the next step to an Italy with no mafia.
Lucrezia, Cosenza, Italy