The former MP entered guilty pleas to two counts of supplying or administering a drug (not cannabis) to another person.

The matters have been listed for sentencing submissions on April 11.

Outside court, Speirs said he had wanted to “bring the matter to a conclusion as quickly as possible”.

“That’s the best thing for me at a personal level, and that’s why I’m taking this approach,” he said.

“I am focused on moving through this process as quickly as possible and that has influenced the approach that I’m taking.”

Speirs has been embroiled in controversy since he quit the leadership on August 8, declaring that he had “just had a gutful” of leadership speculation and did not have the energy to keep fighting.

On September 9, News Corp published a video purportedly showing Speirs snorting a powder.

He declared the footage to be a “deepfake” and vowed to clear his name.

Speirs was arrested at Berri, in SA’s Riverland, on September 26 and charged after police searched his Kingston Park home.

On October 5, Speirs released a video statement saying he did not believe he could “adequately and effectively serve my local community while also dealing with this matter, protecting my mental health and supporting my family and friends”.

“Since allegations of illicit substance use in my home became public, my home has been raided by armed police, I was arrested and I was questioned,” he said.

Speirs has previously said that serving the electors of Black was “the greatest privilege of my life … and I will miss it”.