Raids worldwide as police from several nations reveal vast hack of criminal encrypted phones

International law enforcement agencies on Tuesday revealed a vast three-year global operation to infiltrate encrypted phones with violent criminal groups, resulting in hundreds of arrests worldwide.

Unveiling the "world's most sophisticated" sting, agencies from Australia, Europe, New Zealand and the United States said they "operated" the supposedly secure "AN0M"-enabled phones.

Dubbed "Operation Trojan Shield", forces in 16 countries monitored as members of the mafia, Asian crime syndicates and outlaw motorcycle gangs discussed drug deals, money laundering and even gangland hits.

In Australia alone, 224 people have been charged as part of the operation, which Prime Minister Scott Morrison said had "struck a heavy blow against organised crime -- not just in this country, but one that will echo around organised crime around the world".

As well as gaining the ability to decrypt messages in real time, the FBI and others are said to have launched an elaborate plot to encourage suspected criminals to use AN0M cryptophones.

The devices had no email, call or GPS services and could only message other AN0M phones, could only be bought on the black market and required a code from an existing user to access.

Australian media reported that agencies helped distribute the phones to known suspects — including an Australian fugitive drug boss on the run in Turkey — in a bid to gain trust.

"Criminals needed to know a criminal to get a device," the Australian Federal Police said in a statement.

"The devices organically circulated and grew in popularity among criminals, who were confident of the legitimacy of the app because high-profile organised crime figures vouched for its integrity."

The operation was borne from the FBI's infiltration of similar systems called "Phantom Secure" and "Sky Global", which allowed them to access the communications of tens of thousands of users including top-level crime suspects.

"The closure of those two encrypted communication platforms created a significant void in the encrypted communication market," said New Zealand police. To fill the void, they added, "the FBI operated its own encrypted device company, called 'AN0M'."

At the same time, rumours about the vulnerability of a rival service called "Ciphr" circulated.

It is not clear whether AN0M was entirely the creation of law enforcement or came under their control.

The Australian Federal Police said that as a result of the operation, a total of 224 people were now facing more than 500 charges in Australia alone, while six underground drug labs were shut down and firearms and Aus$45 million (US$35 million) in cash was seized.

"We allege they are members of outlaw motorcycle gangs, Australian mafia, Asian crime syndicates and serious and organised crime groups," federal police commissioner Reece Kershaw said.

"We allege they've been trafficking illicit drugs into Australia at an industrial scale."

New Zealand Police said it was the "world's most sophisticated law enforcement action against organised crime to date".

Detective superintendent Greg Williams said 35 people had been arrested across the country on 900 "serious drug dealing, money laundering and other conspiracy-type charges" and were due to appear in court Tuesday.

Police in New Zealand seized methamphetamine, firearms, and millions of dollars in cash and assets during the operation.

"Warrants are coming in and we expect a number of other arrests to be undertaken," Williams told reporters in Auckland.

More arrests were also expected to be announced around the world, Australian police said.