Fifteen suspects were arrested in Australia, Sweden, Spain and Germany during the Sweden-led operation against companies used as cover by crime gangs to launder drug trafficking profits.
According to Europol, the network stretched from Europe to Asia and Australia.
"This case shows what organised crime looks like today," said Andy Kaag, head of Europol's European organised crime centre.
"It started with something small - two mobile phones seized from a trafficker in a small Swedish town. But what investigators found inside was not a local story. It was a global criminal enterprise."
What grew into a major international collaboration called Operation Candy began in 2024 with the seizure of the phones, said Mats Berggren, deputy chief of the Swedish police.
He did not name the town, citing the ongoing investigation.
But local police found data stored on the phones relating to a sophisticated global criminal network, Berggren added.
Investigators in the four countries worked together for two years, culminating in this week's raids and arrests co-ordinated by Europol.
Dozens of buildings were searched and computers and telephones, among other items, were seized.
The operation was also supported by the European judicial authority Eurojust and authorities in Thailand, where members of the network ran online drug trafficking, mainly to Scandinavian countries.
The drugs were then distributed in Sweden and the profits were laundered through a sophisticated system of transfers via legal companies, investigators said.
In Germany, police seized 1.2 metric tons of synthetic drugs that were due to be shipped to Australia.
The drugs were destined for Melbourne in a shipment that arrived in April 2025, AFP Commander Chris Woods told a press conference on Friday.
Two people were subsequently arrested in Melbourne, and other suspected key figures were taken into custody in Sweden and Spain.
The authorities "prevented an alleged criminal syndicate from ruthlessly exposing the Victorian and Australian communities from immeasurable drug harm," Cmdr Woods said.
"Australia's insatiable appetite for illicit drugs fuels the greed of organised crime globally," he said.
According to Europol, most of them had not previously been on the police's radar.
