Drug-tainted swimmer Shayna Jack has vowed to prove her innocence after a briefing in Brisbane on her positive test to a banned substance.

Jack spent almost five hours in the briefing with Australian Sports Anti-Doping Authority (ASADA) officials on Friday.

Shayna Jack arrives at the ASADA briefing.

AAP

When the 20-year-old emerged, flanked by mother Pauline and lawyer Paul Horvarth, Jack was positive about her battle to avoid a ban.

“I’m not going to stop until I prove my innocence,” Jack said.

Australian swimmer Shayna Jack (centre) at the Brisbane Aquatic Centre in Brisbane.

AAP

“I’ll fight to get myself back into the pool because that’s my dream.”

Jack is facing a four-year ban after testing positive to Ligandrol, a muscle growth agent, during an Australian swim camp last month ahead of the world championships in South Korea.

She has denied knowingly taking the drug but faces an uphill battle to avoid serving the full ban.

It’s expected ASADA will provide Jack’s legal team with a letter outlining the case against her in four-to-six weeks.

“We will leave no stone unturned in preparing her defence to this case,” Horvarth said.