Italian prosecutors said on Wednesday that 61 suspected mafia members were arrested for alleged crimes including fraud, infiltrating government and even extorting onion growers.

A police sweep focused on various family clans of the 'Ndrangheta, Italy's wealthiest and most powerful mafia based in the poor southern region of Calabria, where the syndicate maintains a virtual stranglehold over the population.

The widespread investigation targeted 167 individuals, 33 of whom were already in prison, allegedly involved in mafia crimes within the Calabrian province of Vibo Valentia, public prosecutors said in a statement.

Hundreds of 'Ndrangheta members and their white-collar helpers from that province – including some of those named on Wednesday – are already facing justice in a massive "maxi-trial" currently in its second year, brought by the same anti-mafia prosecutors.

The probe leading to Wednesday's blitz helped map out "roles, tasks and dynamics of the leaders, promoters, organisers and participants of the mafia associations", prosecutors said.

The investigation highlighted the mafia's various business interests and its ability to maintain relationships with "'white collars', politicians and representatives of public administrations", they added.

The various schemes operated by the 'Ndrangheta clans, prosecutors allege, include not only drug trafficking and weapons possession but also vote-buying, interfering in public tenders, fraud related to migrant centres, extorting tourist businesses and the illegal grazing of herds on private land.

Last week, police across Europe staged a vast anti-'Ndrangheta operation, arresting 132 people across the continent, plus Brazil and Panama, on suspicion of crimes including drug and arms trafficking, money laundering and tax fraud.

Although the 'Ndrangheta operates in more than 40 countries, its pervasive influence in the Calabrian economy has made it near impossible to eradicate, helped by its deep pockets from the cocaine trade and cosy ties with the powerful.

In the current case, mafia members managed to infiltrate Vibo Valentia's public health system, hand-picking certain health directors under their control and managing the food service contracts for hospitals, prosecutors said.

One fraud scheme involved migrant services, in which the 'Ndrangheta submitted invoices for non-existent transactions supposedly for the care of migrant children, defrauding the state by more than 400,000 euros (around US$440,000), according to prosecutors.

Within one municipal administration, a public official "adjusted" the results of a public job competition in order to hire a manager close to the mafia, they said.

Garbage collectors in two towns were forced to pay 48,000 euros per year to each of two different clans, while even the growers of the area's famous Tropea red onions were extorted, as were tourist businesses along the coast.

Other more rural crimes by the clans included inserting themselves as intermediaries in the private sale of land, and illegal grazing.

Police said they had managed to document an important 'Ndrangheta summit held during a wedding reception at a coastal tourist hotel, in which members discussed the division of illicit proceeds and the settling of possible disputes.

Wednesday's blitz also involved suspects in the region around Rome, Lazio, and the northern regions of Lombardy, Piedmont and Venice. (AFP)