New Zealand Rugby Bosses have admitted that two prominent All Blacks abused prescription sleeping pills during the 2011 Rugby World Cup but have denied that it is common practice among their players.
New Zealand Rugby Union (NZRU) chief executive Steve Tew said Israel Dagg and Cory Jane had "let themselves down" when they took pills on a night out in Auckland just before the All Blacks' quarter-final against Argentina.
Tew denied the drug abuse, details of which only emerged after media reports on Thursday, had been covered up, saying it was dealt with at the time.
"The incident that occurred that night was at a level that was dealt with internally by the team, we weren't covering anything up," he told reporters.
At the time, reports said the pair went on a drinking binge at an Auckland bar and were seen swaying and slurring their words.
Radio New Zealand reported on Thursday that players were mixing sleeping pills with alcohol or energy drinks to achieve an amphetamine-like high that does not breach doping codes.
It said that Jane and Dagg were not the only All Blacks to take such sleeping pill cocktails and the practice remained "prevalent at Super Rugby level".
Tew disputed this, saying the NZRU had not encountered any more cases since the World Cup, which the New Zealanders went on to win.
However, he said the organisation had surveyed coaches, doctors and others involved in elite rugby to see if they were aware of any issues.
"Our guys live in a very tight environment for a long period of time," he said.
"While we don't know about everything that happens in a team environment, it is hard to keep too many secrets."
He said the NZRU had no plans to introduce testing for sleeping pills, a move Australia's National Rugby League adopted this week.
Tew said that when properly prescribed by medics, sleeping pills had a legitimate function helping players adjust to the high level of travel in Super rugby, which involves games in New Zealand, Australia and South Africa.
"It would be a big call to take sleeping pills out of our tool kit for teams travelling through multiple time zones constantly many times a year when you are expected to perform the next day in a very physically demanding game," he said.