Scarlets coach Nigel Davies says games are being ruined by some players cheating in scrums.
Davies voiced his frustration after his side's 9-9 draw against Ospreys on Saturday was marred by scrummaging infringements and disruption.
"There are lots of cheats going on which unfortunately can ruin a game," said Davies.
"It's a frustration for a lot of coaches at the moment. It's an area of the game that we just can't play off."
The majority of the scrum problems on Saturday came between Scarlets prop Rhys Thomas and his Ospreys opponent, Duncan Jones.
Both were penalised at various stages by French referee Mathieu Raynal, but Davies believes too much guesswork dictates how officials control the set piece.
And he has called on the authorities to tackle the problem to ensure greater consistency and clarity for everyone concerned.
"We have laws, we have interpretation of laws," he said. "We have referees who interpret laws and we have coaches who interpret laws.
"Between all of that mix we're not getting a game that's got any consistency in terms of how it's played or refereed.
"So I think we need to look at it. The coaches need to be involved, the referees need to be involved and we need to have a clear understanding about some of these contentious areas.
"There are not a lot [of them] - the scrum is one and so is the contact area. If we sort those two out and have clear understanding of what to expect from each other there, and then we can move the game forward."
According to Nigel Whitehouse, referee performance and development officer at the Welsh Rugby Union, players need to take responsibility for their actions and listen to the instructions given by the referee.
But he conceded that a strong referee is needed to control the scrum and that new laws could soon be implemented by the International Rugby Board to ensure the problem does not escalate.
He said: "We are looking at law changes being put forward for next year and I know they [the IRB] are doing a lot of research in relation to the scrummaging to see if we can make it better.
"It is a blight on the game. People are not going to come to the Ospreys, Blues, Scarlets or Dragons if all they are going to be watching are collapsed scrums.
"It's so negative and puts people off. I thought it spoiled the game on Saturday night."