December's operation targeted the 'Ndrangheta families based in the southern Italian city of Locri in the Calabria region - the rural, mountainous and under-developed 'toe' of Italy's boot and the heartland of the worldwide crime group.

Despite intense police attention and frequent arrests, the 'Ndrangheta - which derives its meaning from the Greek word for 'heroism' - has continued to extend its reach.

Notoriously ruthless, the 'Ndrangheta has surpassed Sicily's Cosa Nostra and the Naples-based Camorra to operate on all continents thanks to the wealth it has amassed as the principal importer and wholesaler of cocaine produced in Latin America and smuggled into Europe via north Africa and southern Italy.

That trade is worth billions and previous police operations have indicated that the 'Ndrangheta has well-established links with Colombian producer cartels, Mexican crime gangs and mafia families in New York and other parts of North America.

In 2016, a suspected 'Ndrangheta boss, Ernesto Fazzalari (left), was arrested after two decades on the run, fleeing a life sentence for murder. A year later, another suspected boss of the crime clan, Santo Vottari (right), was detained in Calabria having been on the run for a decade

The organisation's tight clan-based structure has made it hard to penetrate, but police have made some in roads in recent years.

In 2015, 163 people were arrested in a major crackdown on the notorious mafia gang, which by that time had become the most powerful crime organisation in the country.

In another sting that year, police snatched assets worth £1.4billion from the 'Ndrangheta, which included more than 1,500 betting shops, 82 online gambling sites and almost 60 companies.

In 2016, one of Italy's most wanted mafia bosses Ernesto Fazzalari was arrested after two decades on the run, fleeing a life sentence for murder.

The 'Ndrangheta member was captured in an apartment in a remote part of the southern region of Calabria.

On the run since 1996, he was convicted in absentia in 1999 of mafia association, kidnapping, illegal possession of weapons and a double homicide linked to a bloody 1989-91 feud which left 32 people dead in his home town of Taurianova.

His arrest was hailed by the government as a significant victory for the state in its battle against the powerful mafia group.

Last year, another suspected boss of the crime clan, Santo Vottari, was detained in Calabria having been on the run for a decade.

He was arrested hiding behind a trap door of a bunker having gone to ground over a 2007 massacre in Germany.

Vottari was convicted in absentia in 2009 of being one of the heads of an 'Ndrangheta clan whose feud with local rivals culminated in the Duisburg killings.

He was given a prison term of 10 years and eight months, two years after he went on the run.

Vottari was one of 31 people sentenced to prison terms in 2009 in connection with the Duisburg killings, which happened after a vendetta between two clans based in the same village, San Luca, spiralled out of control.

The feud between the Nirta-Strangio and Pelle-Vottari clans reportedly began with an egg-throwing prank in 1991. Reprisals escalated after the killing, on Christmas Day, 2006, of Maria Strangio, the wife of clan leader Giovanni Nirta.

The feud was blamed for at least 16 deaths in total, with the killings in Germany bringing it to international attention.

Giovanni Strangio was convicted in 2011 of being the mastermind and one of the authors of the Duisburg killings.

He was sentenced to life in prison. Seven others were given life sentences linked to the feud at the same trial.

Notoriously ruthless, the 'Ndrangheta has surpassed Sicily's Cosa Nostra and the Naples-based Camorra in influence thanks to its control of Europe's cocaine trade.

The organisation is made up of numerous village and family-based clans based in the rural, mountainous and under-developed 'toe' of Italy's boot.

The name 'Ndrangheta comes from the Greek for courage or loyalty and the organisation's secretive culture and brutal enforcement of codes of silence have made it very difficult to penetrate.

But authorities claimed a major breakthrough last year when they captured Ernesto Fazzalari, whom they described as the last senior 'Ndrangheta fugitive still at large.