Keiron Cunningham unwittingly took a banned substance in an attempt to be fit for last year's one-off Test against Australia, the St Helens hooker said yesterday.
The Wales and Great Britain international also claimed the substance was administered by a dietician employed by the Rugby Football League.
Cunningham was fined £2,500 and suspended for a year after failing a drugs test in June 2002 but the ban was suspended for 12 months due to what the League called mitigating circumstances.
His sample contained traces of the hormone substance, HCG, which Cunningham was told purported to be a fat burner to keep his weight down while he recovered from a broken hand.
"I was under pressure to be fit for the one-off Test against Australia and was told that the substance was natural and approved," he said.
"I agree totally with the high burden of responsibility placed on athletes, but had placed my trust in a supposed qualified specialist and am now paying for the consequences.
"If anything good comes out of this, it's a lesson for all athletes to make detailed enquiries of all medical staff. I am confident that rugby will be a better-run game as a result of this.
"I am grateful to the Saints in supporting me during what has been a traumatic time in my life and am looking forward to regaining my fitness and re-establishing myself at the top."
Cunningham, recognised as the top hooker in the game, missed the start of the season due to a career-threatening elbow injury sustained in last year's Test series against New Zealand.
The RFL confirmed that the dietician, Mike Sutherland, had acted as a consultant member of the Great Britain support staff, but was released from his contract in April after an investigation revealed irregularities relating to his qualifications.
In a statement, the League said: "Even before the investigation concerning Mr Sutherland, the Rugby Football League had introduced a full reappraisal of their appointment system."