Breaking the Premiership salary cap is on a par with performance-enhancing drug use, according to t he Rugby Players' Association.
RPA chief executive Damian Hopley's comments come a day after Premiership Rugby insisted no amnesty is in place regarding investigations into possible salary cap breaches.
The Times has reported that Premiership clubs voted in February to suspend investigations into Saracens and one other club.
Hopley told the Times: "Everyone buys into the principle of the salary cap, we recognise its worth and the purpose it is serving for English rugby.
"We've had comments from leading players in the Premiership that breaking the salary cap is akin to being on the field with someone who is taking performance-enhancing supplements.
"It's just not fair. Either you play by the rules or you don't.
"There is a growing sense of frustration amongst the players. We talk about the values of rugby, well there needs to be mutual respect here about what we are all buying into.
"We want transparency and accountability across everything that we do. As the players are held accountable every weekend in front of the viewers and the fans in the grounds, we want to make sure that is the same across the industry."
Any club breaching the cap would only be identified after being found guilty, with c onfidentiality arrangements in place to prevent disclosure of any ongoing investigation.
"We don't make any comment on any salary-cap investigations which might or might not be occurring," a Premiership Rugby spokesman told Press Association Sport on Wednesday.
"But there is no amnesty in place. The salary-cap system is an integral part of Premiership Rugby and has the support of our clubs."
Points deductions range from four to 40, depending on the financial scale of any breach, and only after a thorough investigation.
Any decision on an alleged breach this season would have to be reached before the final round of regular-season games on May 16 in order to become effective this term.
Under existing rules, Premiership Rugby's salary cap manager has up to five years to initiate action against a club for any alleged breach.
A formal charge would then be lodged and an independent panel convened to hear the case. Sanctions are financial, as well as points penalties.
Widely regarded as the most competitive rugby union league in the world...it can only be the Gallagher Premiership.
12 teams compete in the league over a season, playing every team both home and away, before four move into the playoffs and one is relegated.
The division is becoming more and more exciting as each year passes by so who will be lifting silverware at Twickenham in May?
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