NRL chief operating officer Jim Doyle has confirmed the code's integrity unit is investigating how blood test results from Sydney Roosters players found their way onto the phone of an organised crime figure.

Doyle said he was unconcerned by a Fairfax Media report claiming six Roosters players returned blood test results with elevated readings for Human Growth Hormone (HGH).

He is also comfortable with the club's response after informing the integrity unit of the readings earlier this year.

Two days before their preliminary final against Newcastle, the Roosters stated they had nothing to hide after it was revealed a sports nutrition company was sacked when six players returned tests with elevated readings for HGH.

The company, Nubodi, was hired at the end of last year to help finetune detox diets for players before being dismissed in January.

"We're not concerned, really," Doyle said.

"We were aware of these matters earlier this year. So from my point of view, it's not new.

"There's no reason for us to suspect there's a doping issue there. The (HGH) levels are high but that doesn't necessarily mean that there's a doping issue.

"ASADA are obviously aware of it. They have been for quite some time and I'm not aware that ASADA's actually doing any investigation on their part for those particular matters."

But Doyle said revelations the blood tests of players including Sam Moa, Boyd Cordner and Roger Tuivasa-Sheck ended up on the mobile phone of an alleged crime figure raised concerns.

The trio were later re-tested by the club and did not return elevated levels of HGH and there's no suggestion they acted improperly.

"How that happened, obviously I'm not sure," Doyle said.

"It's not the type of information that would normally be out in the domain and being texted around.

"For us, we'll look into that and try to determine how that took place.

"We've already been speaking to various people about that as to ... where that's come from.

"But certainly the results itself we're aware of and they're not overly concerning to us whatsoever."

The Roosters said in a statement there had been "full voluntary disclosure" with the integrity unit over the matter and they hadn't received any contact from ASADA about the matter.

"As is the case with all clubs, players have been regularly and extensively tested throughout the season by ASADA and the club has fully cooperated with the organisation's routine tests," the statement said.

"We reinforce that the club maintains the absolute highest standards in its own policies and governance and, as a club, we have nothing to hide."

Sean Carolan, who runs Nubodi, has denied the inconsistent growth hormones among some tested players was a result of taking illegal supplements.

HGH, which is used to strengthen connective tissue and reduces the probability of injury, is not only banned by ASADA but illegal in Australia.

The Rugby League Players' Association said it had spoken to one of the Roosters players concerned and would await any further developments before acting.

AAP