A Chinese man and three Hong Kong nationals face life in prison after more than A$1bn ($700m; £500m) worth of methamphetamine was seized in Sydney.
Authorities said 720 litres (160 gallons) of liquid methamphetamine, much of it hidden inside gel bra inserts, was sent from Hong Kong.
Justice Minister Michael Keenan said crime gangs had sought to profit from Australia's "lucrative ice market".
He said it was among the largest drug busts in the country's history.
"Ice" is a street name for methamphetamine in Australia.
Minister Keenan said: "3.6 million individual hits of ice were taken off our streets with a street value of $1.26 billion".
The liquid could have made 500kg (1,100 pounds) of high-grade crystal meth, Australian Federal Police (AFP) Commander Chris Sheehan said.
Mr Sheehan said the AFP worked closely with Chinese authorities as part of Taskforce Blaze, which cracks down on international methamphetamine trafficking syndicates.
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