GREATER Western Sydney players face potential AFL sanctions, with an investigation underway after an anonymous complaint about an end-of-season function.

The League and the Giants have confirmed they are looking into what happened at the event last month, days after the club's season ended with the semi-final loss to premiers Brisbane.

"The AFL and GWS have been undertaking an investigation into the Giants players' post-season event, which is in its final stages," the League said in a statement.

The AFL and the Giants have not confirmed what prompted the investigation, or what action the League might take.

GWS released a statement late on Tuesday, saying: "the Giants are aware of an anonymous allegation of inappropriate behaviour at the players' end-of-season function last month.

"The club and its integrity unit have been working with the AFL's integrity unit to investigate."

GWS had a straight-set exit last month after finishing fourth in the regular season, blowing leads in their qualifying final against Sydney and the home semi-final against the Lions.