ESSENDON will ask the Australian Federal Police to investigate the legitimacy of a letter at the centre of footy's doping probe.

The Bombers have been told the alleged letter, purportedly from the World Anti-Doping Agency to former sports scientist Stephen Dank, did not come from the agency.

WADA also confirmed to the Herald Sun yesterday in an email that it did not give permission to Dank to use the anti-obesity drug AOD 9604.

The Bombers believe they may have been duped into using the banned drug, and will seek legal advice in a bid to clear their players of doping sanctions.

But the Bombers concede their players have taken banned drugs. "We will be exploring all our options," a Bombers figure said yesterday.

Demetriou this morning calls for patience

In another day of drama, it emerged:

ZIGGY Switkowski's internal review into Essendon's governance has been delayed several days because of a minor legal matter.

THE report does not call for the heads of coach James Hird or chief executive Ian Robson.

SOME Essendon players were prescribed a weekly injection of AOD 9604 for all of the 2012 season.

A SECOND substance, known as Thymosin, was also injected weekly into some Essendon players.

WADA's email puts Dank and Essendon on a legal collision.

Bombers officials have admitted to ASADA investigators some of their players took AOD 9604 last year, but only because they claim they were shown a letter by Dank, and allegedly read by club doctor Bruce Reid.

But WADA yesterday told the Herald Sun it had sent no such letter.

"Please be advised that a Steve Dank, from the University of Sydney, contacted our science department inquiring about a substance," a WADA spokesperson said.

"As per policy, he was asked to contact the relevant national anti-doping agency (ASADA) for consultation."

WADA claims Dank was referred to ASADA for advice on the S.0 category of banned substances.

The S.0 category states substances not approved for human use are prohibited at all times.

WADA also confirmed it had never informed anyone, not just Dank, that AOD 9604 was not banned.

The denial comes a week after WADA president John Fahey said he would be "extremely surprised" if the international body had issued an approval.

Essendon claimed it did not have the letter, and believed Dank had the only copy.

It is understood Melbourne also claimed it was shown a letter of approval from Dank. The Demons would not comment yesterday.

The Bombers said last night they could not discuss Switkowski's report.

The report has not recommended any terminations of positions, although that could change when the ASADA-AFL investigation is completed in the next several months.

"'The club cannot discuss the report until the recommendations are made public, which we look forward to doing as soon as possible," chairman David Evans said.

Responding this morning in Adelaide, AFL boss Andrew Demetriou called for patience.

"We need to await the outcome of the ASADA report," he said.

"I know that's frustrating to people, but they haven't even begun interviewing players yet.

"They will start that process as I understand within the next week or so.

"At the moment, they are currently finishing interviews with coaches and other officials.

"None of that has been made public, so I do think people should be very careful about some of the commentary.

"Particularly in light of the fact that we haven't even had one player interviewed yet."