The NRL's head of football Graham Annesley said the change was in line with reverting to one on-field official, which he says has given referees more confidence.

Previously a referee has acted as a senior review official in the bunker with assistance from a former player as a review official collaborating to make the calls.

But from Thursday night it has been simplified to one 'bunker review official' - all of whom are NRL referees.

Annesley explained a disagreement between officials over an obstruction call in the lead-up to a Roosters try on Saturday night caused a 'no try' verdict, which he says was the wrong call.

And while it did not cost the defending premiers in their 42-12 win over Newcastle, it's not the first time this season the bunker has got an obvious call wrong.

Just two weeks out from the finals Annesley is not willing to risk ruining a team's season should the same error be made again.

"Earlier this year the change from two on-field referees to one has simplified officiating, resulting in a high standard being maintained so far this season," he said.

"Referees have demonstrated increased confidence to make their own decisions," Annesley said.

"Similarly, by reducing the number of people involved in the review process, we feel bunker officials will also feel more confident in making decisions without consultation, thereby avoiding potential conflicting views or doubt that may on occasions be created by the involvement of a second review official.

"Importantly though, these changes will be invisible to our clubs and fans on game day.

"The primary expectation of everyone involved in the game is to see the Bunker make prompt, accurate decisions.

"They have no interest in what happens behind the scenes so they will notice no difference during games other than what we believe will be improved decision-making."

The changes will give the NRL an immediate but small cost-cutting benefit, and will be reviewed at the end of the season.

Australian Associated Press