The Australian Associated Press reports eight Canadians and two Australians are in custody.
Police said the weekend arrests followed the seizure last month in Melbourne of 650 kilograms of pseudoephedrine that had been hidden in vanilla powder jars.
They said the chemical came from India and is used to produce crystal meth.
Three of the Canadians — Catherine McNaughton, 30, Edmond Proko, 46, and James Kelsey, 27 —appeared in a Melbourne court today charged with drug trafficking. They're due back in court in January.
The 18-month investigation known as Operation Diamondback involved Australian federal and state law enforcement agencies.
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