Greenberg made no apologies for issuing Cronulla coach Shane Flanagan and Wests Tigers boss Justin Pascoe with the league's intention to remove them from the league for serious rule violations.

Flanagan received his breach notice for "constant and consistent" communication with Sharks officials while suspended in 2014, with Pascoe speared over "misleading" the NRL around salary-cap issues involving club great Robbie Farah.

Greenberg said the Tigers should have declared a $639,000 payment to Farah for serving as a club ambassador once he retired.

"I can't tell you how frustrating it is to be here again proposing penalties for breaches of the game's rules," Greenberg said.

"You will recall that in 2016 we imposed a $1 million fine and other sanctions on Parramatta for breaches of the salary cap.

"Last year we fined Manly $750,000 and imposed salary-cap penalties for the same thing.

"Across these two matters, we removed the registrations of seven club officials.

"So it is extremely disappointing that clubs are looking to gain an unfair advantage by deliberately flouting the game's rules.

"I've not reached these preliminary findings lightly. We understand the impact this will have on Mr Flanagan and on the Sharks as they prepare for the 2019 season, but we cannot stand by and allow the game's rules to be broken."

Greenberg said it was clear that hefty financial penalties were not deterring clubs from rorting the salary cap and issued a firm warning to all 16 chief executives.

"The (ARL) Commission has asked me to review the penalties for salary-cap offences. That means looking at increased fines, increased suspensions and stripping clubs of competition points," he said.

"The biggest penalty, ultimately outside of (losing) your livelihood, is (losing) competition points and, if we have to get there, we will.

"We will do and we will take whatever steps are required to protect the integrity of our competition."

The spate of domestic violence and sexual assault charges against NRL stars is also troubling the league.

"I'm very disappointed at having to deal with those sorts of issues," Greenberg said.

"The game is very strong in its stance on domestic violence, but these are issues that are very serious police charges and you must allow those processes to take place.

"We trample on the judicial system but we will have plenty to say and we will make those (penalty) decisions at the end of that process.

"The majority of our players do a phenomenal amount of work across the game, but where players make poor decisions, there have to be consequences and those consequences have to be material."

Australian Associated Press