Australian police have arrested four Chinese men in Sydney in connection with an online investment scam that defrauded more than A $150 million worldwide, with most of the victims in the United States.

Their ages were 27, 24, 19 and 19.

The alleged investment scam was "very sophisticated". Police allege they registered Australian companies with the Australian Securities and Investments Commission (ASIC) to enhance the legitimacy of the fraud and set up Australian business bank accounts to launder the proceeds of crime. In addition, the hackers manipulated legitimate electronic trading software provided to clients by licensed Forex brokers.

Police said the group used dating sites, employment sites and messaging platforms to gain the trust of victims before mentioning investment opportunities.

Victims are then directed to fraudulent and legitimate investment apps that deal with forex and cryptocurrencies.

"The (allegedly) highly sophisticated scam involved the illegal manipulation of legitimate electronic trading platforms, which are usually licensed to forex brokers who then provide the software to their clients," a police spokesman said.

The apps were "maliciously manipulated" to display false returns on investment.

The group then recruited victims to subscribe to financial investment services and manipulated the data to encourage further investment while concealing that their money had actually been stolen.

The men, aged 24 and 27, were arrested at Sydney and Melbourne airports as they tried to fly to Hong Kong on one-way tickets. Police described the two men as the "Australian controllers of the group". They were each charged with one count of dealing in proceeds of crime worth $10 million or more.

The United States Secret Service (USSS) notified the Joint Police Cybercrime Coordination Centre (JPC3), led by the Australian Federal Police, in August 2022 of Australia's links to the largely U.S.-based scam. Subsequently, the Australian Federal Police Cyber Command, in collaboration with the New South Wales Police, launched a parallel investigation code-named Operation Wickham.

This led the Criminal Assets Task Force to freeze $22.5 million in 24 bank accounts allegedly linked to the criminal syndicate.

Investigators found that the syndicate used Chinese nationals living in Australia, mainly students, to carry out various activities to build the infrastructure needed to facilitate its fraudulent activities.

Detective Sergeant Salam Zreika, of the Australian Federal Police's Cyber Crime Operations Eastern Command, said: "Do not make forex, cryptocurrency or speculative investments with people you have only encountered in the online environment. If you're not sure, get an opinion from a professional."

U.S. Secret Service Attache Ike Barnes said, "This joint investigation between the Australian Federal Police and the U.S. Secret Service is a prime example of law enforcement cooperation against a transnational organized crime organization that seeks to exploit international borders in hopes of avoiding detection and arrest."

The two men arrested last week have been remanded in custody and will reappear at Downing Centre Court on January 18, 2023. The other two 19-year-old men are next scheduled to appear at Downing Centre Local Court on January 19, 2023.