For Nicola Gratteri, the lead prosecutor in Italy's largest anti-mafia trial in more than 30 years, the fight against the mob has always been a personal issue.

"I have known the mafia since I was a child because I was hitchhiking to school and I often saw dead bodies on the road," he told AFP ahead of the opening Wednesday of the landmark "maxi-trial".

"I thought: when I grow up, I want to do something so that this won't happen again."

More than 350 people are going on trial in Calabria, the heart of the feared 'Ndrangheta organised crime group, accused of everything from murder to drug trafficking, money laundering and mafia association.

Gratteri is one of Italy's most high-profile anti-mafia prosecutors
Gratteri is one of Italy's most high-profile anti-mafia prosecutors AFP / Alberto PIZZOLI

A call centre in the town of Lamezia Terme was specially converted to host the proceedings, which Gratteri expects to last one year but which many believe will stretch on for far longer.

The prosecutor grew up in Calabria, from where the 'Ndrangheta has extended its reach across all parts of the world, surpassing Sicily's Cosa Nostra as Italy's most fearsome crime syndicate.

"I know the 'Ndrangheta well from inside, because when I was a child I was at school with the children of mafia bosses," Gratteri said.

"The kids I played with then became mobsters and then became drug traffickers. So, that's why I'm familiar with the criminal philosophy, the way of thinking of the 'Ndrangheta members, and this helps in my work," he added.

The 62-year-old has spent three decades under police protection
The 62-year-old has spent three decades under police protection AFP / Alberto PIZZOLI

Gratteri said he felt "very confident" that his case would stand up in court, in what promises to be a long and complicated trial, with more than 900 witnesses just for the prosecution.

It focuses on the Mancuso, a clan based in the Vibo Valentia province, as well as on the politicians, lawyers, businessmen and others accused of enabling them.

Gratteri, 62, has spent three decades under close police protection, and is one of Italy's most high-profile anti-mafia figures.

He is often compared with Giovanni Falcone and Paolo Borsellino, star prosecutors who worked on Italy's first mass trial against the Mafia in the 1980s.

That trial, leading to hundreds of convictions, dealt a major blow to Sicily's Cosa Nostra, but cost Falcone and Borsellino their lives as mobsters killed them both in retribution.

Gratteri said his anti-mafia efforts were being supported by the gradual breakdown of "omerta", the mafia code of silence, among ordinary Calabrians.

"Over the last years we have gained a lot of credibility, a lot of trust. People have started to cooperate, the people are standing by us, are starting to believe in us," he said.