The New Zealand Rugby Union have confirmed All Blacks Cory Jane and Israel Dagg were under the influence of sleeping pills during their infamous night out during the 2011 Rugby World Cup.
In Shanghai, Prime Minister John Key expressed disappointment that players could be involved in such misconduct.
"The thing with the All Blacks is they're arguably our most iconic sports team and the players are ambassadors not just for the sport but for New Zealand young people in particular."
NZRU chief executive Steve Tew said today he believed the pair had been involved in a "silly" competition to see who could stay up the longest in the build up to the Cup quarter-final against Argentina.
The incident made headlines at the time as being fuelled by alcohol, but at no point was the use of sleeping pills mentioned publicly by All Blacks management.
Tew denied that was a cover up, saying the issue of sleeping pills in sport was not a "red flag issue" at the time.
"It wasn't a cover up. These are private employment matters too. Remember we are bound by some stringent legislation as is everybody else in this country is," he said. "The incident that occurred that night was at a level where it was dealt with internally by the team."
The All Blacks had been confounded by Jane and Dagg's actions at the time with their main concern the fact they were out drinking a few days before such an important match.
"At the time we struggled to understand how taking a sleeping pill could keep you up late at night and getting into trouble. It still seems counter intuitive doesn't it.
"They were drinking. There's no question about that. At the time there was mention of sleeping pills but the key was they were out past the curfew, they were drinking two or three days before the quarterfinal.
"They let the team down, they let themselves down and it was dealt with as we'd expect them to be dealt with... As I understand it it was almost as silly as let's have some sleeping pills and see who can stay up the longest."
At the time it had been viewed as an isolated incident rather than a sign of a wider issue.
That view has changed since revelations the Kiwis rugby league side had used a cocktail of sleeping pills and energy drinks at their World Cup last year.
Tew was unsure if Jane and Dagg had done the same in 2011 when they were seen acting strangely in a bar in Takapuna.
"I do not know there were any energy drinks involved, I was not the bar person involved so I can't tell you."
Tew said it remained unclear how common the practice was in rugby, but there had not been any similar incidents he was aware of since 2011.
"If it happened now with the issue we have around the use of sleeping pills and energy drinks ... then we would have probably taken a different course of action, but at the time it was not a hot topic."
The NZRU were investigating the practice, but were not calling for a ban on sleeping pills or prescription drugs in rugby.
Sleeping pills were administered on an "as needs and very scarce basis", but were an essential tool for players operating in a sport that required them to regularly fly through multiple time zones.
"For people who travel in and out of time zones on long haul flights, sleeping pills are used by some people in a clinical sense in that regard."
Tew said the NZRU's medical staff were highly trained and trusted, licensed and lived by a high set of moral standards.
Key said he expected the players would be punished.
"You'd have to leave that to the management of the All Blacks but I'd be amazed if they didn't take anything other than a dim view of it," the prime minister said.
"If it is true I think it would be very disappointing for a couple of players who are actually hugely talented."
- Fairfax Media
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