MELBOURNE (Reuters) - Australian anti-doping investigators will interview about 30 National Rugby League (NRL) players as part of an ongoing probe into the use of banned performance-enhancing drugs in sport Down Under, the NRL said on Wednesday.

Australia was rocked by the release of a report last month that alleged "widespread" doping among professional and amateur athletes, with multiple players and top-flight teams implicated.

Investigators have since spoken to officials at six clubs in the top-flight NRL competition and the game's governing body said the Australian Sports Anti-Doping Authority (ASADA) had turned their attention to the players.

"This is about approximately 30 players who will be issued with notices as people who ASADA needs to talk to in order to understand what is going on," Australian Rugby League commission chairman John Grant told reporters at a media conference.

"There are no clubs being considered to have any systemic issues beyond what is already known."

One NRL club, the Sydney-based Cronulla Sharks, has already stood down their head coach and sacked four other club officials including their team doctor.

The club said the sackings stemmed from "management failures", rather than the use of banned substances, though media reports said players had been offered compensation if they waived their rights to sue the club over drug charges.

The NRL said the interviews would take from four-six weeks to complete, but declined to name the players or clubs involved, citing the ongoing investigation.

Any players found by ASADA to have breached anti-doping provisions would be served an "infraction notice" and be called to appear at an NRL tribunal, Grant added.

The probe also extended to the NRL's rival code Australian Rules, with the Essendon Bombers club, one of the oldest teams in the popular Australian Football League, under investigation over their administration of supplements to players.

(Reporting by Ian Ransom; Editing by Peter Rutherford)

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