The man, standing in the Wanderers' active supporter bay at Allianz Stadium, was filmed by Network Ten cameras at fulltime in Saturday's match, which was won 2-1 by Sydney FC.

Initially the man gives the middle finger toward the camera before quickly turning into the apparent salute.

New laws brought in during 2022 make the gesture illegal in NSW with a maximum jail term of 12 months.

"Officers from Surry Hills Police Area Command are investigating reports of a spectator making an offensive gesture at a sporting event held at Moore Park on Saturday," NSW Police said in a statement.

"Police are urging anyone who may have information about this matter to contact Surry Hills Police Station or Crime Stoppers on 1800 333 000."

The Wanderers declined to comment.

The incident comes after a Melbourne Victory supporter was issued a five-year ban by FA for the use of the gesture at the same ground in the club's Unite Round fixture.

Even prior to the new legislation, FA had typically taken a zero-tolerance approach to such incidents.

FA issued a lifetime ban to a person who used the gesture at the 2022 Australia Cup final between Sydney United 58 and Macarthur.

Three supporters of Sydney United fronted a Sydney court last week in relation to Nazi gestures used at that game.

All three pleaded not guilty, with magistrate Joy Boulos set to deliver her decision next month.

Australian Associated Press