A prison guard has made some extraordinary claims about Cassie Sainsbury's behaviour.

A prison guard who works at the Colombian prison where 22-year-old Australian Cassie Sainsbury is behind bars has accused the alleged drug trafficker of being a “liar”.

Speaking to 9 News under conditions of anonymity, the female guard says the young prisoner has been feeding “bad information” to the media.

"Cassie likes attention and she know how to get it," the guard, who has been working in the Colombian prison system for six years, said.

"She's not my most difficult prisoner, but I don’t like her lies and the bad information she's giving to the media."

Over the weekend, in her first interview since her arrest, Cassie told News Corp Australia she "feared for her safety" after an image of her posing with a fellow inmate was leaked to the Australian press.

"I made a complaint to the guards about it," Cassie said about the image, which shows her smiling next to an unidentified prisoner.

"I didn't give permission for a photo to be sent out and they confiscated a mobile phone."

The prison guard told reporter Seb Costello they were under the impression Cassie was more than happy to take the photograph.

"She is bullying another prisoner for taking a picture with her...but we believe Cassie wanted to take the picture," the guard said.

She also said Cassie was lying about not having proper access to healthcare and doctors while inside Buen Pastor jail.

"That's a lie. Every prisoner gets checked out for their health. She has access to private doctors too if she wants," she said.

After Cassie's fiancé was denied a visit to her yesterday, her mother and sister are expect to seek legal advice on whether they will visit her in prison today.

However, the Daily Telegraph reports the 22-year-old may refuse the visit after her family members are believed to have signed a $1 million to share her story with the press.

Last week, she told News Corp Australia she was "annoyed" her mother and sister had reportedly signed a deal without asking her first.

"It's my story. They need to get permission from me to sell my story," she said.

South Australian Cassandra Sainsbury was arrested on charges of drug trafficking at a Bogota airport last month.

LISTEN: There's a reason why we are all so obsessed with Cassie Sainsbury's story.