Italy's top anti-Mafia prosecutor and Australian police are warning that the massive diversion of law-enforcement resources to combat terrorism is eroding the fight against the Mafia and other serious organised crime groups.

Australian authorities have failed for decades to dismantle the "board of directors" of Calabrian Mafia godfathers across Australia, allowing them to entrench their drug trafficking operations, build alliances with outlaw bikie gangs and infiltrate government and police agencies.

A 2013 multi-agency police report warns "Ndrangheta Transnational Australian Groups" are posing an extreme risk to Australia.

Italian anti-Mafia magistrate Dr Nicola Gratteri has also warned that the Australian government has risked allowing these organised crime groups to prosper.

"When social alarm is provoked over terrorism, governments are forced to invest in terrorism and not in Mafia … the Mafia celebrates because they know there are fewer resources," Dr Gratteri said.

Senior police across Australia have confidentially backed these comments, saying that while terrorism was a clear priority, the focus on suspected jihadists had meant the shifting of important resources away from the fight against organised crime.

Three weeks ago, Dr Gratteri oversaw an international anti-Mafia operation, codenamed Santa Fe, which attacked the operations of the powerful Alvaro Mafia clan, seizing tonnes of cocaine and making dozens of arrests.

Confidential Italian and Australian police files state that the Alvaro clan has powerful cells operating in Australia, allegedly headed by Adelaide construction figure, Paul Alvaro, 64, and a NSW man. Mr Alvaro did not answer specific questions, but he denies any links to organised crime

The pair is aligned to a handful of figures in capital cities across the nation and in Griffith, NSW, who - according to a police assessment - operate as "an executive Board of Directors" for the Calabrian Mafia, or "Ndrangheta".

The board "comes together on an ad hoc basis particularly in times of crisis or when the low profile of [the Calabrian Mafia], so carefully cultivated and jealously protected, is threatened," police reports say.

NSW Police intelligence lists "the main" Calabrian Mafia clans as "the Sergi family, Trimboli family, Romeo family" who are all "based predominantly in the Griffith area." Only a very small number of members of these families are engaged in crime and there are many Italian families who share these common surnames but who are not connected to the Calabrian Mafia.

"The criminal activities engaged in by this network have been engaged in for decades with a high level of success. Members of the network have occasionally been apprehended and imprisoned, but on the whole, internal wrangling appears to have exacted a higher toll, as family members are murdered not infrequently," says one NSW police assessment.

In Victoria, court files allege that wealthy Melbourne businessman, Giuseppe "Bebbe" Manariti, was linked to the world's biggest ecstasy importation in Melbourne in 2007.

Commonwealth prosecutors have alleged that Mr Manariti was briefed by the Mafia importers, stating that he was "interested in unfolding events" linked to the massive shipment.

Mr Manariti, who has never faced criminal charges, is a close associate of alleged Melbourne Mafia boss Tony Madafferi and the pair, along with deceased Mafia leader Rosario Gangemi, are considered by police to have previously formed a "trinity" that directed the Calabrian Mafia's Melbourne operations.

Both Mr Manariti and Mr Madafferi were previously identified in a top secret 1995 anti-Mafia operation as members of the group also known as the Honoured Society.

Mr Madafferi could not be reached for comment but has previously denied any involvement in organised crime. Mr Manariti could not be reached for comment.

The police files also reveal that the Calabrian Mafia has built close ties to outlaw motorcycle gangs (OMCGs), including the Rebels and Bandidos.

"This is particularly evident with identified connections to the Sydney and North Coast Bandidos OMCG and the Canberra and Batemans Bay Rebels OMCG. There is also intelligence of links to the Finks OMCG through associates."

Dr Gratteri's warning about the diversion of resources away from the organised crime fight echoes a classified National Crime Authority report in 2003.

"It is suggested that they [Australia's Mafia cells] will neither decline nor cease their activities in the foreseeable future due to their long entrenched history in criminality in Australia, the steady market demand for cannabis and other illicit drugs and the diversion of law enforcement efforts to other areas."

Watch part two of a joint Fairfax and ABC Four Corners mafia investigation on ABC1 8.30 PM Monday.