Port Adelaide forward Jeremy Finlayson has admitted making a homophobic slur during his side's win over Essendon and is under AFL investigation. 

Finlayson has apologised for the incident, which happened in the third term of Port's 69-point win over the Bombers on Friday night at Adelaide Oval.

It is understood an umpire's microphone picked up the insult and at least one Essendon player also called it out.

"I take full responsibility for what happened Friday night," Finlayson said in a statement.

"The word I used is very unacceptable in the game of football. We need to stamp it out and I'm very remorseful."

The 28-year-old made the club aware of the remark during the three-quarter time break, and spoke with the victim on the field to apologise after the final siren.

"I knew straight away that it was not acceptable and I take full responsibility," Finlayson said.

"I addressed it at the time and … let everyone know what happened, and it's now in the hands of the AFL to investigate.

"I'm continuing to reflect and improve myself, getting all the education I can to make myself better."

The AFL confirmed on Saturday night that Finlayson was under investigation.

"We are taking this matter extremely seriously," an AFL spokesman said.

"AFLIU [integrity unit] are now investigating and we will provide an update once that investigation is completed."

South Australia Premier Peter Malinauskas said it was a credit to Finlayson that he owned up to his mistake.

“People make mistakes we all do as human beings and I think it’s a great credit to Jeremy that he has apologised quickly, he owned up to the mistake he has made and I think that’s an action of someone who has done the wrong thing and acted with integrity following it," Malinauskas said.

"Obviously people will make commentary on how disappointing it is, but here we have a young man who's made a mistake and owned up to it.

“We all make mistakes, all of us are human and Jeremy's acknowledged that."

Last month, North Melbourne coach Alastair Clarkson was fined $20,000 and has a suspended two-match ban for abusing St Kilda defenders Jimmy Webster and Dougal Howard during a pre-season game.

Clarkson was asked to explain his actions to the AFL after allegedly using the homophobic slur "c*** s*****" during the practice match.

AAP