Cassie Sainsbury has revealed how she feared for her life while spending three years in Columbia's notorious El Buen Pastor prison.

The drug trafficker-turned-fitness influencer, 28, has revealed she was stabbed and beaten multiple times by fellow inmates while discussing her appearance on the new season of SAS Australia.

'[SAS] was nothing that I expected. Obviously everyone goes into SAS thinking it's not hard instantly but I was transported straight back to prison,' she told Fitzy and Wippa with Kate Ritchie on Monday.

Host Ryan Fitzgerald asked: 'Were there moments where you feared for your life in prison?'

'Definitely. I had a lot of beatings. I got beaten up a lot. I got stabbed. I got two stab marks on my arms where I was stabbed,' Cassie responded.

'I went through a lot of things that I wouldn't wish on anyone ever.'

'Why were you stabbed?' Michael "Wippa" Wipfli asked.

She explained: 'I had a lot of enemies. And obviously being the gringa in a Spanish prison, it just brings that attention of you know, rich white girl. Need to I guess bully her down until that's it?'

Cassie was arrested in Columbia in April, 2017, when she was caught trying to leave the country with 5.8kgs of cocaine in her luggage.

The bust shot her to international infamy as she was dubbed 'Cocaine Cassie' and even landed a role on SAS Australia this year.

She was sentenced to six years behind bars at El Buen Pastor prison but only served three before she was released.

Cassie spent another two years on parole in South America before returning to Australia last year to live in Adelaide with her wife Tatiana.