Working with their counterparts in Dubai and the Netherlands, Australian Federal Police (AFP) said they had smashed the drug ring with simultaneous arrests early Tuesday morning in Sydney and Dubai.
Ten suspects were taken into custody in Sydney, while police in the United Arab Emirates arrested five Australians, including two living in the city, the statement from the AFP said. Police in the Netherlands arrested two other people.
"A total of 1.8 tonnes (1.98 tons) of MDMA, 136 kilograms (300 lbs) of cocaine and 15 kilograms (33 lbs) of crystal methamphetamine was seized by authorities in the Netherlands before it could reach Australia," the statement said.
The potential street value of the drugs, should they have made it to Australia, was up to 810 million Australian dollars (around $650 million).
The operation began around a year ago, targeting organized crime groups which dealt in tobacco and drug smuggling, and the AFP alleged that the gangs had attempted to smuggle the drugs into the country in a number of container shipments since November 2016.
"A united response from law enforcement and partner agencies in Australia and overseas is critical to our efforts to dismantle organized criminal networks,"AFP Assistant Commissioner Neil Gaughan said.
"The people we allege are part of this syndicate are Middle Eastern organized crime figures that are well-known to law enforcement, and for decades this group has flaunted their wealth and activities, telling the community they were untouchable. Today, it should be obvious that they are not."
Assistant Commissioner Mal Lanyon added that, in addition to the drug seizures, investigators also confiscated firearms during the some 30 searches carried out in Sydney.
Those arrested in Australia will be charged with conspiracy to import a "commercial quantity of a border controlled drug" and "dealing in proceeds of crime and money worth $1,000,000 or more," among other offenses. Maximum penalties for the crimes range from 25 years to life.