AHMED Saad has been named as the player at the centre of a banned substances investigation by the AFL.

The 23-year-old was formally named by St Kilda on Wednesday afternoon.

The Saints named him as the "player under review by the AFL for an alleged breach of the AFL Anti-Doping Code" for taking a substance permitted for use "out of competition".

It is believed Saad returned a positive 'A' sample and the results of the 'B' sample are yet to be determined.

Until that is the case, no action can be taken.

St Kilda said further tests will be conducted on the substance "in the near future" and that Saad had inadvertently taken it.

"Ahmed is surprised and extremely disappointed to find himself in this position, after returning a positive sample to a substance alleged to be on the prohibited list in the AFL Anti-Doping Code," the club said.

"The product suspected is permitted for use out of competition but is not allowed to be used in competition.

"The club is bound by confidentiality under the AFL Anti-Doping code and as a consequence cannot make further comment at this time."

On Wednesday morning, the Australian Sports Anti-Doping Authority said it couldn't provide any information. 

"When and what we can say about an individual athlete is strictly governed by our legislation," an ASADA spokesperson told AFL.com.au.

"Under its legislation ASADA is unable to provide further comment at this time."

Saad could face suspension if found to have taken a banned substance.

Richmond's Justin Charles was found to have taken an anabolic steroid in 1997 and was suspended for 16 weeks.

More recently, VFL player Matthew Clark was suspended for two years after he was found to have dimethylamylamine in his system after a game.

His suspension was initially nine months but that was extended after an ASADA appeal.