NRL referees have been instructed to be stricter with ruling the defensive 10 metres this season, after complaints of inconsistencies were raised by coaches last season.

While the overall feedback from coaches relating to the two-referee system – introduced in 2010 – was positive, referees’ boss Bill Harrigan said there were concerns over discrepancies in how far the whistleblowers would take back a defensive line.

“We found that with the two referees, occasionally you would have one who would set a 10 metres where the other (in the same game) might bring defenders back 12 metres for example,” Harrigan told AAP.

“We had some spectators who’d mentioned it, a couple of coaches had highlighted some examples and we also noticed in our debriefs that there was a little bit of inconsistencies in our 10 between the two refs in our game.

“We have acknowledged this and we thought we could rectify that in 2012.”

Harrigan said some of the responsibility would be put back on players who have been incorrectly lining up in previous years by only placing their back foot in line with the referee – rather than having their body mass in line, as outlined in the rules.

“This year, I’m asking the clubs to get out of the habit of just putting their foot back in line with the referee,” Harrigan said.

“They should now line up their body mass, which is what the rule is – you’re supposed to be behind the referee.

“If we go back 10 and a player goes back and only puts his back foot in line with the ref, then he’s probably only about nine metres.

“So all we’re asking them to do is come back in line with the referee.

“And from there, we’ll keep it as consistent as we can between the two refs in each game.”

Also coming under the spotlight in 2012 will be the controversial “cannonball” tackle, which gained notoriety last season with a string of incidents involving players diving at the legs of an opponent who has already been tackled.

Under the 2012 guidelines, referees will call a penalty if “a player forcefully spears his body at an opponent’s legs in a dangerous manner”.

Harrigan says it will be up to the referees’ discretion what will be deemed “forceful”, however he felt the game took giant steps last season to outlaw the ugly tackle.