He believes the integrity of top-flight rugby will suffer if cases of cap abuse are swept under the carpet.
Premiership Rugby opened an investigation into alleged transgressions last year, but it was understood to have been scrapped, only for the issue to be reignited following heated exchanges between the clubs.
Players are at risk of being caught in the crossfire but Rugby Players’ Association (RPA) chairman Day told The Rugby Paper: “If we’re going to play to a salary cap, I want, 100 per cent, that to be investigated and I want the investigation to be known to the players.
“We want a level playing field and it’s not fair if one, two, three or four clubs are breaking the rules to the ones that aren’t. The salary cap is there for a reason – it keeps the game competitive and ensures financial stability.”
The Rugby Paper believes certain top Premiership clubs are prepared to challenge the salary cap under European law if action is taken against them over historic breaches, for which heavy fines and a 40-point deduction could be applied.
RPA chief executive Damian Hopley recently issued a stark warning against abolishing the cap, arguing: “A minimum of four of the Aviva Premiership clubs would be out of business by the end of this coming season and mass redundancies would ensue.”
Northampton lock Day added: “It would change the game because clubs with rich backers would bring in loads of Southern Hemisphere talent and buy out all the best English players.
“Suddenly you’ll have a real gulf in class between our clubs and we don’t want that. The Premiership is so competitive now and that’s the way we’ll keep improving crowds, clubs and the finances around the game.
“As a players’ board we were asked what we thought of the salary cap and it was unanimous that it’s a good thing. We want to see it increased with revenues so players can maximise earnings, but, if we’re not sensible, clubs will go bust.”
The RPA are near to completing a deal with the RFU and Premiership Rugby that from 2017 will provide top players with a minimum of five complete weeks’ rest at the end of each season.
Day said: “The new standard contract for players is close to being signed and is bringing in a mandatory off season, which is a good step.
“We mean five weeks’ total rest. We don’t want players still having training programmes or targets to meet.”
Day also welcomed the introduction of head injury assessment protocols in A-League and Championship.
“It’s fantastic the protocols have been extended. Concussion is now being taken very seriously,” he said.
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