All Blacks goal kicker Beauden Barrett caught moving ball behind ref's back

Beauden Barrett has been caught out by a sharp-eyed South African rugby supporter.

Pieter van der Spuy spotted the All Blacks star stealing metres behind the referee's back prior to his one successful penalty kick in the team's 16-16 draw with the Springboks on Saturday.

All Blacks captain Kieran Read opted for a shot at the posts when referee Nic Berry awarded New Zealand a penalty near the 22m line in the 48th minute of the match. But, as van der Spuy pointed out when he posted the video on Twitter, Barrett rolled the ball approximately four metres closer to the posts when Berry's back was turned.

"Watch closely what Beauden Barrett does with the ball as he prepares for the penalty kick," van der Spuy captioned the clip, which has been viewed more than 120,000 times.

Barrett ended up kicking the penalty straight down the middle to give the All Blacks a 10-6 lead early in the second half.

But while other Springboks supporters were angered by his action, suggesting the All Blacks cheated by moving the ball closer to the posts, Barrett may have actually made the kick harder for himself.

Given the penalty was on the 22m line, he was always going to have the range. But by moving the ball forward, the No 15 created a much tighter angle for himself.

He missed two other penalty attempts in the match, with Richie Mo'unga eventually taking over the goal-kicking duties when Barrett started suffering cramp in his calf.