An Adelaide Crows player complained that she was sexually harassed by a Greater Western Sydney opponent during the round 4 meeting between the clubs.

The player made a complaint to the AFL, which led to an investigation by the league's integrity unit, but the player who made the allegation did not want to take the matter further.

The GWS player, who was alleged to have touched her opponent on the bottom and made an inappropriate sexual comment, is understood to have strongly denied the allegation when questioned.

It is believed to be the first known complaint about sexually inappropriate behaviour during an official AFL game. The AFL dealt with the matter last week, in the days following the GWS versus Adelaide game at Blacktown in Sydney on February 25, which ended in a dramatic draw.

Sources said that the Adelaide player believed her GWS opponent had "crossed the line'' with a combination of lewd words and touching on the backside.