Hundreds of criminals have been arrested across the world as a result of a three-year operation led by Australian Federal Police (AFP) and the United States Federal Bureau of Investigation.

Dubbed “Operation Ironside”, the sting operation began in 2018 after a similar take-down of encrypted communications provider Phantom Secure, the AFP said.

Operation Ironside involved an encrypted communications platform, AN0M, used by the police to intercept criminals’ communications. The platform was used by organised crime gangs around the world to plan executions, mass drug importations and money laundering.

The FBI gained access to the AN0M app in 2018, and started running it covertly, installed on Google Android devices that criminals sold to each other.

“The app AN0M was installed on mobile phones that were stripped of other capability. The mobile phones, which were bought on the black market, could not make calls or send emails. It could only send messages to another device that had the organised crime app. Criminals needed to know a criminal to get a device,” the AFP said.

“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 AFP did not provide details on how the FBI managed to get access to the AN0M app.

The police said they were able to read millions of messages in "real time" describing murder plots, mass drug import plans and other schemes.

The operation has led to drug trade arrests in 18 countries across Asia, North and South America, Europe and the Middle East. The Australian police arrested more than 200 people - members of outlaw motorcycle gangs, Australian mafia groups, Asian crime syndicates and serious and organized crime groups.

They have also seized “3.7 tonnes of drugs, 104 number of weapons, $44,934,457 million in cash, and assets expected to run into the millions of dollars.”

“More than 4,000 members from the AFP and state and territory police have been involved in the execution of hundreds of warrants since 7 June, 2021,” the police said.