Australian Federal Police announced on Wednesday that it had arrested eight people in the past two weeks who are accused of the importation and trafficking of heroin, cocaine, and methamphetamine with a value of $21 million into Australia.
Commander Tess Walsh said in a press conference that the bust came after a five-month operation known as Operation Sunrise.
Operation Sunrise targeted an alleged Vietnamese organised crime syndicate based in Melbourne that had been operating for "quite some years".
Police allege the syndicate used cabin crew from Malindo Air, an international commercial airline, to bring drugs into the country. At least two of those arrested were cabin crew.
"The method of bringing these drugs into the country is of significant concern," said Walsh.
"All eight people arrested have faced court and the investigation remains active and ongoing."
Walsh said police had seen a re-emergence of heroin use, particularly in Victoria, which has led to a number of fatal overdoses.
The eight people arrested by police include a 38-year-old woman on January 7 in Tullamarine, and a further six others the next day. A week later a woman from Richmond was also arrested.
Along with the illicit drugs, police seized luxury cars, drug paraphernalia and $100,000 in cash.