The Michael Firrito rushed behind free kick was a "tough call" according to AFL football boss Mark Evans but clubs will be urgently contacted by the league to clarify the rules.

The AFL will warn clubs that the further away a player is from goal when he rushes a behind no matter how much pressure he is under, the greater the likelihood he will give away a free kick.

Tough call: The Michael Firrito decision close to goal. Credit:Getty Images

"The Firrito decision was a tough call because he was certainly under pressure," Evans said of the free kick against the North Melbourne defender from last round which resulted in a goal for Port Adelaide.

"I think we need to give clarity around that to the clubs and Hayden Kennedy will make contact with clubs about that."