The former Salford captain Malcolm Alker faces an investigation by UK Anti-Doping after claiming he took drugs while still playing in Super League.
In his autobiography released next week, the 33-year-old admits taking cocaine and banned growth hormones.
The Rugby Football League passed the information on to the UK Anti-Doping agency, who stated: "Mr Alker's alleged admissions are of interest. We will be seeking to clarify the relevant facts in this matter."
The former hooker, who retired due to injury in 2010, played more than 350 times for Salford and ended his long association with the Reds last year.