Australian police are now in custody of eight Canadians and two Australians, allegedly members of a Canadian-led drug syndicate, AAP reported.
Three of the Canadians arrested on Sunday were identified as Catherine Marie McNaughton, 30, Edmond Proko, 46, and James Wray Kelsey, 27.
They immediately appeared court on Monday as they face charges of drug trafficking estimated at $300 million. They are set to appear at the Melbourne Magistrates Court on January.
Victoria Police Assistant Commissioner Steve Fontana told AAP that the Canadians arrested were believed to be travelling to Australia to supply drugs for the syndicate.
"This is a significant international syndicate that's been targeting Australia. We're very pleased with the outcomes of the investigation," Mr Fontana said.
However, it cannot be confirmed whether the drug syndicate is actually selling drugs to locals or merely transporting drugs inside Australia.
In September, Australian police had seized 650 kg of pseudoephedrine hidden inside vanilla powders. As part of the operation, detectives discreetly replaced the drugs inside the jars. They kept the "drug" seized in a self-storage unit in South Melbourne and keep eye on the activities of the drug syndicate until such time they can catch them red handed.
Meanwhile, a local report from Toronto's The Star, stated that as early as 2012, the Australian Federal Police had been conducting the "Operation Diamondblack". The arrest of the eight Canadians and two Australians Monday were all part of this operation.
In November, AFP arrested a Canadian man (identity withheld for security reason) whom they believed to be the organiser and financier of the syndicate. "Operation Diamondblack" sprang from this arrest.
"Let me tell you, these are significant players in an international organized crime syndicate that's targeted Australia. Three hundred and fifty kilograms is not the greatest record in Australia, but it is certainly very significant given the impact we've had on the network and how high up these people are within the network," Mr Sharpe said in an interview with The Star in 2012.
Foreign Affairs spokeswoman Amanda Reid said that the Canadian consulate in Sydney is giving the arrested Canadians the proper "consular services" and that consulate staff were already in contact with Canadian authorities.
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