Port Adelaide utility Jeremy Finlayson has admitted on Saturday night to making a homophobic slur towards an unnamed Essendon player less than 24 hours earlier.

The AFL had started an investigation after Friday's night clash between the two teams before Finlayson's club released a statement addressing the issue.

Finlayson, in the Port Adelaide media release, said he felt remorse about the using the unknown remark and claimed he apologised to the rival player post-game.

"Jeremy Finlayson has admitted to making a homophobic slur against an Essendon opponent during the third quarter of (Friday) night's game at Adelaide Oval," the club said.

"A contrite Finlayson made the club aware during the three-quarter time break and apologised to the victim on field after the final siren.

"Finlayson, who will be counselled by club leaders in the coming days, will provide a statement tomorrow. "The club will wait for the AFL to complete its investigation."

While the club has not said what words the Yorta Yorta man was alleged to have said, the AFL has started probing the details behind homophobic slur.

The microphone of one of the umpires allegedly picked up Finlayson's comment.

Some Essendon players apparently also reacted to the slur at the time.

The AFL plans to run its process through its independent integrity unit.

"We are aware of an alleged comment made by a Port Adelaide player in last night's match against Essendon," AFL spokesman Jay Allen said in a statement.

"We are taking this matter extremely seriously.

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

Finlayson was one of the Power's better players in the side's 69-point victory over the Bombers, kicking 3.1 up forward from 19 possessions.