Australian Federal Police have uncovered a scam in which a Perth couple were unknowingly used as drug mules.

Police say the couple, aged 64 and 72, travelled to Canada after being told they had won a free holiday, including seven nights' accommodation and new luggage.

They became suspicious on their return to Perth and alerted Customs officers who found 3.5 kilograms of methamphetamine hidden in each of their suitcases.

A 38-year-old Canadian man was arrested at Perth airport and has been charged with importing a commercial quantity of methamphetamine.

The case is part of a larger investigation by Australian police, freelance reporter Peter Hadfield told CBC News from Sydney today.

"There's a lot of Canadians involved in this, it seems," he told CBC's Heather Hiscox. "We’ve had eight arrests over the last 18 months."

Canadian ring

He added: "It was certainly a Canadian ring that was at the heart of it, and I imagine we'll be getting more details coming out as the weeks go on."

Cmdr. David Bachi of Australian police said they do not believe the couple was willingly involved.

"The investigation has revealed a complex and highly organized scam in which older Australians appear to be targeted by a bogus Canadian-based tour company identifying themselves as Auscan Tours," Bachi said.

"The organizers of this scam went to great lengths to provide a facade of legitimacy.

"Thankfully, the travellers contacted Customs and didn't dismiss their concerns, allowing us to make the arrest.

"We will continue working with local and international law enforcement partners, targeting all elements of this drug syndicate."

Travellers warned

"Victims of this scam or any persons who have received similar offers of travel should contact the AFP immediately."

Jan Hill, the director of Customs Airport Operations in Perth, warned travellers about carrying luggage on behalf of someone else, no matter the circumstance.

"If you've been asked to carry something on behalf of another person, make the right choice and alert local authorities," Hill said.

"Do not allow another person to pack your bag and do not carry luggage on behalf of another person."

Australian police say investigations into the incident are continuing.

The maximum penalty for this offence is life imprisonment.

With files from CBC News