Richmond coach Damien Hardwick has questioned the umpires' reasoning behind not paying his side a 50-metre penalty in the final stages of their narrow AFL loss to Sydney.

The Tigers trailed by six points on Friday night when Dion Prestia was awarded a free kick 65m from goal as the final siren sounded, a split second after the whistle had blown.

Swans midfielder Chad Warner gathered the ball as soon as the siren went and booted it into the crowd, which might have resulted in a 50-metre penalty to Prestia, who had not yet taken his free kick.

The umpires decided Warner had not heard the whistle amid the chaos and Prestia's shot from long-range ultimately fell well short of the goal that would have levelled the scores.

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"He couldn't have heard, common sense, OK?" officiating umpire John Howarth told a Richmond player at the time.

Hardwick played a straight bat in his post-match media conference, refusing to blame the umpires' call for the Tigers' loss after they threw away a big lead.

But the Tigers' three-time premiership coach took to social media on Saturday morning with a post that read: "Common sense. Sorry, what?"

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On Saturday, the AFL stood by the umpires' decision.

"The AFL confirms the decision late in last night's match to not pay a 50m penalty was correct," the league said in a statement.

"The free kick to Richmond player Prestia was correctly paid (by the non controlling umpire in the centre of the ground) and almost immediately after the free kick was paid, the siren sounded.

"The umpires then made the correct call in not applying a 50m penalty against Swans player Warner, given the immediacy of the free being paid, the siren sounding and the ball being kicked into the crowd.

"It is the same discretion often used around the ground when umpires don't believe a player has heard the whistle and kicks the ball."

The latest controversy comes after a week in which premiership coaches Simon Goodwin and Chris Scott defended umpires from growing criticism.

AAP