JUST when the NRL thought they had the controversial grapple tackle under control, officials are now bracing for its latest incarnation - the crippler.

The new and improved wrestling move, which targets players' pressure points, started as a training ground rumour, but it has developed enough legs to have NRL officials issuing blanket warnings to clubs that the manoeuvre will be penalised and players will be punished for anything resembling it.

Still faced with a battle to rub out the original grapple as well as the crusher - which appeared late last season - out of the game, officials are intent on ensuring that the crippler does not spread.

The NRL was careful to word its response to the threat yesterday, although chief operating officer Graham Annesley admitted he heard about a month ago that the move - which aims, like its predecessors, to immobilise attackers and slow down the play-the-ball - might be in its infancy.

"We're not aware that any clubs are actually training to do it, or practising to do it, but it has been mentioned," Annesley said. "It's nothing more than a rumour at the moment, and we're not overreacting to simply a rumour. However, if any club, at any time, decided that they would do something like that, the judiciary would have ample laws under the provisions of contrary conduct to take suitable action.

"The referee can take any action on the field for anything they believe is against the spirit of the game. The judiciary can charge anything which is against the spirit of the game or contrary to the image of the game. These catch-all provisions have been in the rules for a long time."

Officials refused to be specific about which clubs might be practising the manoeuvre, and rather than admonish any coach for attempting to flout the rules, referees coach Robert Finch said he expected it.

"With every change of rules, their major role as a coach is to look to find other ways to gain an advantage," Finch said. "The bottom line is that, most of the time, we are always reacting to those things, and we have been since 1908. But I think we're now better equipped to recognise changing strategies and deal with them."

The move has not been reported by any referees who have taken charge of pre-season trials, but Finch admitted he had spoken to every club about the league's continuing clampdown on grapple tackles.

Meanwhile, the push towards having two referees controlling NRL fixtures continued yesterday, with Finch admitting he was planning to introduce dual officials to first-grade at some stage this season.

The system was introduced in last Friday night's Manly-Melbourne trial and will again be used this weekend in two trials - the Bulldogs against St George Illawarra and Souths against Cronulla. Finch said he was planning to use the concept in the new National Youth Competition, as well as dead rubber NRL contests this season.

"I think it's a positive step forward," Finch said. "We've got to understand now that we're dealing with full-time professional players who are probably bigger, stronger and faster than they've ever been … We need to ensure that officials can match that."

The system was trialled in 2002, with little success, although officials maintain it has far more support this time, from coaches as well as referees.