Watch: Kiwi RWC ref in hot water after giving Fijian player low-five while they were beating Wallabies

Kiwi rugby referee Ben O'Keeffe is being called out by Australian media for committing a "cardinal sin" while officiating Satruday's Rugby World Cup clash between the Wallabies and Fiji.

O'Keeffe has been snapped on camera from multiple angles giving Fijian fullback Kini Murimurivalu a low-five moments after the Flying Fijians scored a try, pushing their lead to 21-12 over the Wallabies.

As the fullback gets close to O'Keeffe, the Kiwi official offers his right hand for the hand gesture which Murimurivalu obliges to.

FOX Sports Australia labelled the action "the cardinal sin as an official".

"Regardless of his intensions or the motivations behind the gesture, it just shouldn’t happen," the outlet said in their story, which they headlined "Playing favourites, bro?".

That was the last time Fiji would score in the match as the Wallabies went on to make a comeback and win the encounter 39-21.