AUSTRALIAN Federal Police are yet to receive a complaint from Essendon over the legitimacy of a letter purporting to show WADA approval for banned drug AOD-9604.

It has been alleged that sports scientist Stephen Dank showed a letter to the Bombers confirming the drug was a legal substance.

"To date, the AFP has not received a referral from the Essendon Football Club," an AFP spokesperson told AFL.com.au.

"Should a referral be received, the AFP will consider the matter in accordance with normal process."

Dank's legal team has refused to address a News Limited report that said Essendon would call in federal police over the letter.

It has been suggested Essendon doesn't have a copy of the letter and that Dank could be in possession of the only copy.  

"In the face of no allegation made by any relevant prosecuting or investigatory authority, we have nothing to say," Dank's lawyer Greg Stanton told AFL.com.au.

"At this point in time there's no relevant allegation against my client and accordingly we've got nothing to say," he said.  

Stanton said there was no guarantee Dank would make any further public comments.  

"I'm not going to commit my client to any possibility until we see what actually occurs."

Former Telstra chief executive Ziggy Switkowski has completed an independent review of Essendon's governance, practices and procedures, but its release has been delayed.

Matt Thompson is a reporter for AFL Media. Follow him on Twitter @MattThompsonAFL