The masonic-esque initiation ceremony of new mafia affiliates was captured on camera for the first time by Italian detectives investigating the 'Ndrangheta crime syndicate, a powerful clan headquartered in the impoverished southern region of Calabria.

A would-be-mafioso is seen as he takes an oath in front of a gun and a suicide pill that he is instructed to swallow if he is ever coerced to betray his new clan.

The ground-breaking footage was recorded by Carabinieri police with a hidden camera. Carabinieri are the national military police of Italy.

"In this holy night, in the silence of the night and under the starlight and the shining moon I create the holy chain. With humble words I create the holy society," a mob elder says in the video to start the ritual known as the Santa (Holy) bestowal.

The elder then asks the new gang member to deny all of his family's prior crime affiliations "up to the seventh generation".

The oath is taken in the name of three Italian nationalist figures of the 19th century: unification hero Giuseppe Garibaldi; politician Giuseppe Mazzini; and army general Alfonso La Marmora.

Police said the names of the three historic figures are used in place of those of high ranking clan members - respectively the boss, the accountant, and a figure known as the '236th day Master'.

The video was released by Milan prosecutors as they announced the arrests of 40 suspected 'Ndrangheta operatives, including a teenager, in the northern Lombardy region.

Prosecutor Ilda Boccassini told a news conference that it was the first time the Santa bestowal was recorded on camera.

Boccassini explained that the footage provided authorities and the public with unique insight on the rites and formulas used by crime syndicates, as the ritual was previously known to authorities only through the accounts of mafia supergrasses (police informers).

"The affiliation is something [mobsters] have in the DNA, under their skin. They can get away from 'Ndrangheta only by cooperating with authorities or through death," said Boccassini.

The probe was part of a series investigations led by Milan police that have revealed how 'Ndrangheta has increased its presence in the industrial north in recent years.