The mother of an Adelaide woman who has been arrested and detained in Colombia for drug trafficking maintains her daughter is innocent and has hit out at those who she says have framed her.

Cassandra Sainsbury, 22, was arrested after being found in possession of 5.8 kilograms of cocaine as she waited at El Dorado International Airport in Bogota to fly back to Australia, her sister Khala said.

Ms Sainsbury was arrested on April 12 after an X-ray machine detected the cocaine hidden in her luggage.

Her family have described her as "naive", and said she could be facing up to 25 years in prison.

Australian woman Cassandra Sainsbury was detained at Colombia's major airport. ( Supplied: StarNow/ Cassandra Sainsbury )

Her mother told KIIS FM her daughter was given a package that she believed contained headphones, and she put it into her luggage without questioning it.

"The day of her departure he came up to her hotel gave her a package that was wrapped in black plastic and she took it and put it in her luggage," she said.

"And this is where the naive bit comes in, she didn't even rip it open to make sure there were headphones in there."

She said they had engaged a local lawyer.

"If she pleads guilty the minimum is six years," Ms Evans said.

Ms Sainsbury's mother (L) said she could not believe someone could do this to her daughter. ( Supplied: StarNow/Cassandra Sainsbury )

An Adelaide lawyer who has previously represented Australians charged with drug offences overseas said Ms Sainsbury may not get a trial for three or four years if she did not plead guilty.

Human rights lawyer Stephen Kenny said the defence costs in such a situation could be up to $30,000.

"I've had a brief discussion with a lawyer in Colombia," he said.

"Probably if it's a guilty plea the matter could be dealt with in about six months, but if it went to trial if she pleaded not guilty it could be up to three years before the matter is finalised."

'She is just so scared', mother says

Earlier this morning, Ms Evans told the Today show she could not believe someone could do this to her daughter.

"Cassie is just, 'I didn't do it mum, you have got to get me out' and crying hysterically," she said.

"She is just so scared that she is caught up on the other side of the world for something she didn't do with no support over there, no nothing.

"The anger inside of me that someone could do this to an innocent girl for their own gain and to destroy several lives, not only Cassie's but her family's as well ... I don't know how a person could do that."

Ms Sainsbury has worked as a personal trainer in Adelaide. ( Supplied: StarNow/ Cassandra Sainsbury )

Khala Sainsbury said her sister, who has worked as a personal trainer in Adelaide, was in Colombia on a working holiday.

An online campaign, which has raised more than $2,000, has been set up by the family to help raise money to pay for legal costs.

"Cassie would never do anything like what she has been accused of," Khala wrote online.

"Anyone that knows her, would say she is a kind, loving, happy kind of girl. She would help anyone out in need."

Trial to take place in two months' time

Drug laws in Colombia Penalties for possession, use, or trafficking of illegal drugs are severe, and convicted offenders can expect long prison sentences under harsh conditions.

Penalties for possession, use, or trafficking of illegal drugs are severe, and convicted offenders can expect long prison sentences under harsh conditions. Serious offenders must remain in the country to serve a lengthy parole period, during which they are given no housing and may lack permission to work — as they are neither a citizen nor a resident.

Serious offenders must remain in the country to serve a lengthy parole period, during which they are given no housing and may lack permission to work — as they are neither a citizen nor a resident. Family members must often support the offender, sometimes for more than a year, until the parole period expires.

Family members must often support the offender, sometimes for more than a year, until the parole period expires. Drug crimes account for the third most common reason for imprisonment in Colombia.

Drug crimes account for the third most common reason for imprisonment in Colombia. Between 42 and 48 per cent of the country's female prison population are behind bars having been accused of drug offences. Source: Transnational Institute study of Drugs and Democracy

Ms Sainsbury was denied bail and would face trial in two months, the family said.

Khala said Ms Sainsbury was being held in Colombia's largest women's prison.

"Our hearts break, because we know she is innocent," she said.

According to her sister, Ms Sainsbury was planning her wedding "to the love of her life" and that was now on hold.

The family also said Ms Sainsbury was a volunteer of the Country Fire Service (CFS).

But a CFS spokesperson said she had not volunteered with the service for three years.

The Department of Foreign Affairs and Trade (DFAT) confirmed it was providing assistance to an Australian woman arrested in Colombia, but would not provide further details.