The Sydney Roosters reportedly sacked a sports nutrition company after learning six players, including Kiwis winger Roger Tuivasa-Sheck, had returned blood tests with elevated readings for the banned substance Human Growth Hormone.
In a Fairfax Media report, it is alleged details of the players' blood test results were found on the phone of an organised crime figure after being seized by law enforcement officers.
The firm, Nubodi, was hired by the club last year in an attempt to finetune detox diets for the players, the club's chief operating officer Brian Canavan confirmed.
Canavan said Roosters players were tested for human growth hormone without the consent of club officials or staff.
Boyd Cordner, Sam Moa and Tuivasa-Sheck were three players named in the Fairfax report who had elevated HGH levels.
The trio were later re-tested by the club, with those blood tests not returning elevated levels of HGH.
There is no suggestion any player has acted improperly.
"We were very unhappy that the extended (blood) testing was conducted. It was done without our knowledge,'' Canavan told Fairfax.
The Roosters, who finished the season as minor premiers and are favourites to take out premiership in a fortnight, informed the NRL's integrity unit of the unusual test results midway through this season.
Sean Carolan, who runs Nubodi, denied the inconsistent growth hormones among some tested players was a result of taking illegal supplements.
HGH is banned by ASADA as it is used to strengthen connective tissue which reduces the probability of injury.
The Roosters face Newcastle on Saturday night in a preliminary final, with the winner to progress to the grand final on October 6.