03/05/2017 1:06 PM AEST | Updated 03/05/2017 1:07 PM AEST

U.S. Agency Tipped Off Colombian Police Before Cassie Sainsbury's Drug Arrest: Report

It's now claimed a last-minute plane ticket was purchased by an unknown party in Hong Kong.

The U.S. Drug Enforcement Agency (DEA) tipped off Colombian authorities that Cassandra Sainsbury may be attempting to smuggle drugs out of the country, it has been alleged in new reports.

Sainsbury's last-minute flight to Colombia via London was allegedly purchased by an unknown source in Hong Kong, which raised a red flag with the DEA -- a senior American drug enforcement agency -- The Australian has reported.

The South Australian woman arrived in Colombia on April 3, and the alert from the U.S. came just two days later, according to Channel 7 News. The DEA forwarded Colombian police her photograph and passport details on April 5, and she was arrested when she went to catch her flight back to Australia on April 12.

Sainsbury's bags were searched minutes before she was due to board her flight at El Dorado International Airport in Bogotá. Authorities found 5.8kg of cocaine in her luggage and she was immediately arrested for drug trafficking. If convicted, she faces between 12 and 25 years in prison.

Her family claim she was visiting Colombia on a working holiday and was tricked into putting the drugs in her bag, believing they were headphones she purchased as gifts for her bridal party.

If the drugs had made it back to Australia, experts believe they would have been worth around $2 million on the black market.

According to The Australian, the plane ticket purchased in Hong Kong was one of several red flags that led North American authorities to alert Colombian police.

Bogota airport's head of narcotics, Colonel Rodrigo Soler, said that the young woman's travel profile fit a well-established pattern, but it is possible that she was genuinely duped by drug runners.

"When someone leaves their country for Colombia without a strong justification -- for instance if a person comes to Colombia for two or three days -- that triggers an alert," he told The Australian.

Cassandra Sainsbury with her fiance Scott Broadbridge. The couple were planning to wed in February next year.

The fundraising page set up by Cassandra's sister Khala has now been shut down, after raising only $4,232 of its $15,000 goal towards funding the South Australian's legal costs.

Sainsbury has been denied bail due to the quantity of cocaine she was allegedly carrying, and will remain in El Buen Pastor women's prison pending her trial in two months' time.