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.

AFP Commander David Bachi said police do not believe the couple were willingly involved.

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

"The organisers of this scam went to great lengths to provide a façade 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."

"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," Ms Hill said.

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

The AFP says investigations into the incident are continuing.

The maximum penalty for this offence is life imprisonment.