In his strongest public statements yet on the AFL case, the agency boss of the past six years, whose term ended in November, has told Fairfax Media it is "irrefutable that there was a problem" at Essendon.

To the chagrin of the AFL, the case that spoilt 2013 has intensified again on the eve of a new season, with sports scientist Stephen Dank, who directed programs at Essendon and the NRL's Cronulla receiving a "show cause" letter from the Australian Sports Anti-Doping Authority.

ASADA is believed to have levelled allegations of 34 breaches against Dank over his work at Essendon.

Mr Fahey said that "only the complete evaluation, and then hearing under the WADA rules" will determine whether Essendon footballers committed anti-doping-rule violations. The former New South Wales premier said he remains bewildered that the Essendon case has not been investigated by WorkSafe Victoria. ASADA has not issued show-cause or infraction notices to AFL players or support personnel, but Mr Fahey said this was inevitable.

"In generic terms, I have been led to believe that there is sufficient information there that would lead to infraction notices being issued against a number of people," he said.

"The individuals I don't know. The numbers I don't know. Nor do I need to. Nor do I want to.

"Now they've [ASADA] got to, of course, before issuing those notices, satisfy themselves that the evidence will be sufficient to stand up. But my understanding was that it was heading in that direction."

"Something happened that involved substances that clearly were prohibited. There's no doubt they were prohibited."

Asked about Jobe Watson's comments on television last year when Essendon's Brownlow medallist captain said he believed he was given AOD-9604 in the supplements program, but had been assured it was legal, Mr Fahey declined to discuss individuals.

The status of anti-obesity drug AOD-9604 has been widely debated, but WADA's position is fixed. "I have absolutely no doubt that it's a banned substance", Mr Fahey said.

WADA can intervene in anti-doping matters once a national anti-doping body formalises a case.

In a written response to questions, WADA director-general David Howman said the authority would "continue to watch with interest" the most sensational anti-doping case to hit Australian sport.

"From our point of view the investigation by ASADA is still not complete," he said.

"To ensure the integrity of the process is maintained, and given WADA's right of appeal once the process is complete, we cannot comment further at this stage."

Mr Howman said WADA's view is that "ASADA has carried out its investigation pursuant to the Code". Fahey has expressed similar confidence in the government-funded body and its outgoing CEO Aurora Andruska who leaves ASADA in May, while others have criticised the authority for acting too slowly.

"They should be given the room to deal with it in an orderly fashion, whatever that means in terms of time," Mr Fahey said.

"The whole world's got their eyes on Australia", and confirmed that message had been impressed on federal Sport Minister Peter Dutton when Mr Fahey and Mr Howman met with the minister last October.

When it emerged last month that Andruska would soon leave ASADA, Mr Fahey endorsed her work but lamented she had encountered what he termed "bully boys" in pursuing the AFL and NRL cases.

Mr Fahey said he had no issue with highly sensitive information being shared between the AFL and ASADA in last year's joint investigation into Essendon between the bodies. However he said it was not helpful to ASADA that a written update requested by the AFL that was delivered last August was labeled the interim "ASADA report".

"It wasn't," Fahey said. "It was a document for AFL use only under their code of conduct as I understand it."