Australian Sports Anti-Doping Authority boss Ben McDevitt has revealed his concern that crucial records of the Essendon supplements program may have been "either destroyed or removed".

In an exclusive interview with Fairfax Media, Mr McDevitt warned of fresh show-cause notices if evidence emerged of document destruction in an attempt to cover-up the use of a banned substance.

Stressing that the authority did not at present have evidence to pursue a case on evidence removal, Mr McDevitt admitted the extraordinary lack of records about the Bomber's 2012 supplements program remained "a troubling issue" for the authority.

Essendon's former sports scientist Stephen Dank has maintained he kept detailed records of the supplements program. But these records have not been found in hard copy or electronic form by the anti-doping authority or the AFL.

Mr McDevitt's comments came the day after an AFL anti-doping tribunal ruled against ASADA's case that 34 past or present players had been given banned drug Thymosin beta-4.

"I believe there are two scenarios," he said. "One is because of the secretive nature of the regime, that no records at all were kept. Or, alternately, if records were kept then they were either destroyed or removed by persons unknown in a bid to get rid of the evidence."

Asked why anyone would destroy such records, Mr McDevitt responded: "Because if the records actually showed what substances were injected, and when.

"I think everybody involved is just so, so surprised at the extraordinary lack of records. My understanding with sporting bodies is that, with their supplements regimes, there's extensive documentation and you would expect to be able to find that. In this case it's just extraordinary that there is no documentation to be found. So, I have a suspicious mind and I'd love to know what happened to the records if there were records."

In response to Mr McDevitt's comments, an Essendon spokesman said the AFL had forensic accounting firm Deloitte seize every computer hard drive and other records at the club as soon as it revealed it had reported its supplements program to the anti-doping authority in February 2013.

The spokesman added that every club official and player was made available to the authority's  investigators and urged to tell the truth. He said the club could not speak for what individuals no longer associated with Essendon may have done with any records they had made.

As reported by Fairfax Media on Tuesday, the AFL anti-doping tribunal slammed the record keeping at Essendon as "deplorable".

The tribunal also noted that "it is the responsibility of the club to ensure that complete and accurate records are kept".

Speaking in a briefing in Canberra that lasted for 50 minutes on Wednesday, Mr McDevitt again called on Mr Dank to produce the records.

"Stephen Dank has publicly stated that extensive records of the injection regime were kept but throughout this investigation no such records have been found," he said.

"Curiously, Mr Dank, in a statutory declaration provided to ASADA in response to a disclosure notice, declared he had no documents to produce."

Later in the briefing McDevitt said that if Dank did actually keep, or have, records of the Essendon supplements program he suspected they would be "chaotic and shambolic".