A senior judge has announced a new hearing to decide if the current plea bargain is still valid, after questioning Ms Sainsbury today in a court in Bogota, Colombia.

Sergio León, a specialist judge who usually deals with especially complex or delicate cases started the hearing by having the prosecutor run through the circumstances of Ms Sainsbury's capture on April 12, 2017.

The plea bargain was then explained: if the deal was accepted by the prosecutor, the defence and the judge, Ms Sainsbury would be sentenced to 6 years of prison instead of the potential 30 year sentence if she was found guilty.

The judge explained, through a translator that given the gravity of the case, he had a responsibility to ask Ms Sainsbury some key questions.

After establishing she was of sound mind via some more simple questions, the judge asked Ms Sainsbury if she had been coerced into taking the plea deal.

There appeared to be some translation difficulty, because Ms Sainsbury responded that she had been threatened into transporting the drugs.

However, this caused a visible reaction from the prosecutors because this information was apparently not part of the plea deal.

Because of numerous conditions imposed by various of the Colombian Penal code on which the plea deal was based, it wasn't clear if the current plea deal could go ahead.

After more questioning, the defence admitted that they did not have any concrete evidence that Ms Sainsbury had been threatened into her actions.

After a lengthy recess, the judge returned and told the court that more investigation was needed to make sure that Ms Sainsbury's plea deal was valid. He then set the new date.

For her part, Ms Sainsbury was composed for the majority of the hours-long hearing, even smiling slightly in parts.

Her mother, Lisa Evans, requested at the end of the hearing to make a public statement to the judge but was barred from doing so by court procedure.

The hearing will reconvene on August 9.

Ms Sainsbury was caught at Bogota's international airport in April, trying to smuggle 5.8 kilograms of cocaine inside 18 separate packages of headphones.

She has been held in a Bogota prison since her arrest, with her case attracting huge attention in Australia.

Sainsbury's sister on Wednesday told Channel 7 in Adelaide the plea deal was the best outcome they could have hoped for.

But Kahla Sainsbury said her sister's life would never be the same, even after just a few years in prison.

"I don't think there's much she can do when she comes back home. It's going to be hard for her to get a job. It's going to be hard for her to do anything," she said.

"Because she's going to be labelled as 'Cocaine Cassie'."

Immigration Minister Peter Dutton said the case served as another warning to Australians travelling overseas.

"People need to abide by the laws of that country. If not, they will face serious consequences," he told Seven on Thursday.

The government provided consular assistance to Sainsbury but did not fund her legal case, Mr Dutton said.

- with AAP

Earlier: Adelaide woman Cassie Sainsbury has agreed to serve six years in jail after striking a plea deal with Colombian prosecutors on drug smuggling charges.

The 22-year-old had been facing at least 20 years behind bars but has agreed to reveal the identities of others involved in the cocaine ring she was working with in return for the lighter sentence.

The deal was revealed in a Bogota court on Thursday morning Australian time, with the judge to decide whether to accept it, Australian media in the court reported.

Sainsbury was caught at Bogota's international airport in April, trying to smuggle 5.8 kilograms of cocaine inside 18 separate packages of headphones.

She has been held in a Bogota prison since her arrest, with her case attracting huge attention in Australia.

Her mother Lisa Evans and fiance Scott Broadbridge were in Bogota to support her during the sentencing hearing on Thursday morning Australian time.

Sainsbury's sister on Wednesday told Channel 7 in Adelaide the plea deal was the best outcome they could have hoped for.

But Kahla Sainsbury said her sister's life would never be the same, even after just a few years in prison.

"I don't think there's much she can do when she comes back home. It's going to be hard for her to get a job. It's going to be hard for her to do anything," she said.

"Because she's going to be labelled as 'Cocaine Cassie'."

Immigration Minister Peter Dutton said the case served as another warning to Australians travelling overseas.

"People need to abide by the laws of that country. If not, they will face serious consequences," he told Seven on Thursday.

The government provided consular assistance to Sainsbury but did not fund her legal case, Mr Dutton said.