Referees have been instructed to penalise players for intentionally passing the ball into defenders lying in the ruck as NRL CEO Todd Greenberg ordered a crackdown on time-wasting.

Parramatta's Will Smith and Brisbane's Anthony Milford were among those last weekend to use the ploy, which is occurring more often as players try to gain a penalty by passing the ball into a defender who hasn't cleared the ruck.

However, Greenberg said players manipulating the rule would themselves be penalised from this weekend, which will be the final round of matches before State of Origin selection.

"I watched some of these examples over the weekend. It was a bad look for the game, and in simple terms, not in the spirit of the game," Greenberg said.

"I've directed the referees – if they see a player like that, deliberately throwing the ball into another, they should give a penalty to the opposition team. You'll see that happen this weekend.

"Sometimes these things happen in the game. But when you see them, you've got to deal with them quickly. What I saw over the weekend looked ridiculous to me – players purposely throwing the ball into a player laying in and around the ruck. If it happens deliberately, teams can expect a penalty."

Greenberg announced a number of other measures aimed at reducing stoppages and time-wasting, including players sent to the sin-bin leaving the field in a timely manner and referees keeping warnings to captains short and to the point.

"I've provided a directive to the referees to ensure that we don't want to see committee meetings on the try-line while we're waiting for the play to restart," he said.

"The onus of responsibility is on the referee to have a very brief conversation, provide a warning to the opposing captain, and to get on with the game. That's exactly what I've told them today.

"I don't want committee meetings on the try-line. If the referee wants to give a captain a warning, make it quick, make it short, make it sharp. Let's get on with the game. That's what the fans want to see."

He also warned of tougher action if players continue to take their time exiting the field after being sent to the sin-bin.

A memo was sent to clubs about the issue last week but there was little improvement last weekend, which saw 14 players sin-binned, including at least one in each match.

"We talked about this at [last week's] competition committee meeting," Greenberg said.

"The starting proposition was to put the onus of responsibility back on the coaches and the players.

"We've said that to the coaches and players – if you get sent to the sin-bin, get off the field and do it quickly. If that's going to continue to delay, then I'll come in over the top and mandate some changes."

Greenberg also declared the crackdown this season on the play-the-ball and teams conceding penalties within 20 metres of their try-line had been a success and would continue.

"That will be determined later in the year, but they're on track, they're on target, and they're doing exactly what they've been told to do by the competition committee," he said.

"I again remind people that the competition committee has people like Mal Meninga, Darren Lockyer and some very experienced current and former coaches and players.

"The directive is simple – make sure players make a genuine attempt to play the ball with their foot, and get them back 10 metres, police the rules.

"We're going to continue to do this, and when there are multiple infringements, we're going to continue to send players to the sin bin. Ultimately, we're trying to do one thing and one thing only – give the fans a better game to watch.

"We will hold our nerve. Now I'm hoping that obviously it gets better and better, and there's a pragmatic approach from both the players and the referees. I think we've found that balance over the last few weeks. Let's hope it continues to improve."

Greenberg said the NRL football department would continue to make decisions aimed at improving the game.

"Occasionally, like players over the course of a weekend, we won't get everything right," he said.

"But we'll jump on it, we'll do it quickly. We've got some very experienced, smart people, who have been in this game a long time, leading the football program here. And they'll continue to do it."