A huge gun-running operation masterminded by the Sicilian mafia is being investigated by senior police officers for potential links to “terrorist activity across Europe and beyond”.

Anti-mafia prosecutors in Catania are investigating the possibility that Cosa Nostra is supplying assault weapons to organised crime syndicates from north Africa and firearms into the hands of extremists in western Europe.

Decommissioned guns legally procured from the same Slovak dealer, Afg Security, which supplied the “mass casualty” weapons used by Islamists in the Charlie Hebdo and Paris attacks of January 2015, as well as the failed terrorist attack on a TGV in France last August, appear to have ended up in the hands of the mafia.

Cosa Nostra members paid £33,000 for 160 deactivated weapons that experts could make lethal in moments. Last month a Catanian couple were arrested over the haul. They belong to the “Ceusi” mafia clan, a family tied to Catania’s dominant Santopaula clan.

The Catanian mafia in turn works closely with the Calabrian ’Ndrangheta, an international criminal network whose mastery of the cocaine market means it has a turnover of £44bn, greater than McDonald’s and Deutsche Bank combined. Italy’s second most wanted mafia boss, Ernesto Fazzalari of the ’Ndrangheta, was arrested after two decades on the run.

Anti-mafia prosecutors in Catania have told the Observer that a number of assault rifles due to be flown from Catania to Malta in June last year appear to have been destined for a prominent Egyptian people-smuggler in Alexandria. Intercepted telephone calls are understood to have documented conversations between members of Cosa Nostra over the transfer of money from Egypt to Sicily, ostensibly for the firearms.

The investigators’ principal concern is that the weapons may fall into the hands of extremists. “The Egyptian citizen was previously arrested in Italy for belonging to an organisation dedicated to human trafficking in the Med. We’ve been investigating possible connections with terrorist organisations,” a carabinieri source said.

Organised criminals are increasingly open to trading with extremists, complicating the battle against terrorism

Renewed smuggling activity around Alexandria has, according to Europol briefings, intensified anxiety that Islamist militants based in the Sinai could also attempt to reach Europe via the Mediterranean.

Investigators believe that some of the 160 AK-47s obtained by the mafia in Catania may have ended up with Europe’s web of black market intermediaries who supply firearms to the criminal underworld.

“We have not found all the weapons yet. The investigation is ongoing but the danger is that they have been distributed by criminal intermediaries and have found their way into the hands of potential terrorists,” said a senior specialist with Europol.

Ballistics experts are aware that petty criminals and drug dealers usually require small pistols they can conceal, while terrorists want assault weapons to inflict maximum damage.

British counter-terrorism officials have been perturbed by recent signs of an ever closer relationship between organised criminals and Islamists. At least one London terrorist cell is known to have sourced a firearm, silencer and ammunition through a London criminal contact. Tarik Hassane, 22, was convicted last April of conspiring to kill on the streets of the capital.

The weapons found in Catania were sold legally by Afg Security but illegally reactivated in Sicily by removing a metal pin hammered into the barrel.

Two months after the guns were found in the Sicilian port – a year ago – a British gang attempted to import the biggest haul of “mass casualty” weapons found on the UK mainland, firearms that were also bought from the same Slovak dealer, Afg. The cache of 22 Kalashnikov-style assault rifles and nine machine guns was found by police in a motorboat off Kent. But Europe’s senior officers also believe that organised criminals are increasingly open to trading with extremists, a development that further complicates the battle against terrorism.

Robert Crepinko, head of Europol’s European Migrant Smuggling Centre (EMSC), which was set up to dismantle the proliferation of criminal networks orchestrating people-smuggling, said that it was possible that British criminals might be working with extremists in north Africa and Egypt. Asked if Europol was examining ties between criminal groups in the UK and Europe and Islamists in Libya, Crepinko responded: “That is a fair assumption. It will remain a very busy area of law enforcement.”

In Libya, it is estimated that between 400,000 and 1 million migrants are waiting to cross to Europe, the first stop often being Sicily. Acquiring intelligence inside the war-racked country is difficult, but at least five jihadi groups – including al-Qaida Libyan affiliate Ansar al-Sharia and Islamic State, which recently lost control of the port of Sirte – occupy territory there.

Although Tim Morris, executive director of police services at Interpol, said they had not collated any direct evidence of Isis being involved in sending migrants to southern Europe, they could not discount it. “We know Isis has a very commercial eye. They need to raise revenue, so I would certainly say it’s a distinct possibility.”

Anti-mafia prosecutor Rocco Liguori added: “It is very possible, because they traffic arms from Italy to this area controlled by Isis.”