The AFL has confirmed Melbourne's Joel Smith tested positive for an illicit substance ahead of the 2023 AFL Finals series, with the league handing down an immediate "mandatory provisional suspension" to the Demons players.

The Demons swingman returned a dirty urine test following his club's Round 23 match against Hawthorn.

Smith was tested by Sports Integrity Australia as part of a routine testing process, one seeking to test for performance-enhancing drugs.

Smith tested positive for a banned substance, said to be cocaine.

While the sample was collected ahead of the finals series, the results of the test were reportedly not known until the completion of the four-week post-season.

"The AFL confirms that a mandatory provisional suspension (which is effective immediately) has been imposed on Melbourne FC player Joel Smith following notification to him by Sport Integrity Australia of an Adverse Analytical Finding (AAF) and a potential violation of the Australian Football Anti-Doping Code (Code)," an AFL statement read.

"It is asserted that a sample provided by Smith during an In-Competition doping control test on 20 August 2023 returned an AAF for the presence of Cocaine and its metabolite Benzoylecgonine being a Prohibited Substance under the Code.

MELBOURNE, AUSTRALIA - JUNE 11: Taylor Adams of the Magpies and Joel Smith of the Demons compete for the ball during the 2018 AFL round 12 match between the Melbourne Demons and the Collingwood Magpies at the Melbourne Cricket Ground on June 11, 2018 in Melbourne, Australia. (Photo by Adam Trafford/AFL Media/Getty Images)

"Smith was tested after the Round 23 Melbourne vs Hawthorn game on Sunday August 20, 2023 and was notified by Sport Integrity Australia last week in relation to the finding. The AFL was made aware of the test results at the same time.

"The matter is now progressing in accordance with the Code, initially involving further investigation by Sport Integrity Australia supported by the AFL.

"In the interim Smith will not be part of Melbourne's football program.

"The AFL is unable to make any further comment at this time."

Bans for testing positive while in-competition can range from a month to as many as four years.

According to News Corp, Smith is expecting to serve a three-month suspension that would be served over the coming months, which would make him available for Round 1 selection next year - with a hearing with Sports Integrity Australia tipped to take place in the next few weeks.

Melbourne released a statement on Thursday morning, accepting the provisional suspension and placing support behind Smith in the wake of the matter.

"THE Melbourne Football Club acknowledges the communication sent by AFL regarding Melbourne Player Joel Smith and the notification to him of an Adverse Analytical Finding, potential violation of the Australian Football Anti-Doping Code and imposition of a Provisional Suspension which is effective immediately," the club statement read.

"As this matter is being investigated by Sport Integrity Australia, the Melbourne Football Club is unable to make any further comment at this time.

"The Club will continue to support Joel throughout the process and ensure our supporters are informed further when we are authorised to do so."

Smith has played 42 games for the Demons since his debut in 2017, managing a career-high 14 games this year.