Australian authorities are warning the public of the dangers of falling for scams that could inadvertently lure them to becoming drug mules for overseas criminal syndicates.

The warning follows a 91-year-old Sydney man, Victor Twartz, being charged in July with importing 4.5 kilograms of cocaine into Sydney from India.

Australian Federal Police (AFP) organized crime commander David Stewart told reporters on Tuesday the man was groomed via social media over a long period of time before he was caught on an arrival flight into Sydney from New Delhi.

A search of Twartz's luggage found 27 packages of soap which tested positive for cocaine.

Twartz told Australian Broadcasting Corporation (ABC) he had met people in New Delhi whom he had befriended online. As he was about to board his plane to return to Sydney, he told ABC that he was handed a bag that he was told contained gifts for someone in Australia.

Stewart said crime syndicates are using social media to target vulnerable Australians, particularly the elderly and mentally ill.

AFP Acting National Manager Aviation Wayne Buchhorn said people should be aware that if you knowingly, or unwittingly, bring drugs into Australia you may be charged.

"Claiming ignorance of drugs hidden inside your luggage does not automatically mean you will not face criminal charges," Buchhorn said.

"People can expect they will be charged if they knowingly bring drugs into Australia, or are reckless or willfully blind to the fact that there could be narcotics concealed inside their luggage or items they are carrying."

The 91-year-old man faced a Sydney court on Tuesday.