Stories run by The Courier Mail over the past two days have alleged a number of behavioural issues at the Lions including illicit drug taking, illegal gambling and match fixing between 2002 and 2009.
The newspaper alleges Jason McGrath, a self confessed drug dealer and cousin of Lions' premiership player Ashley McGrath, claims to have supplied six players with speed, ecstasy and marijuana during that period.
It also alleges the reason for a Lions' player's absence from the team was fabricated to cover up an issue with the illicit drug policy.
The AFL will not be investigating at this stage, however.
"The AFL and its integrity unit are aware of recent claims made to the media regarding the Brisbane Lions between 2002 and 2009," an AFL statement said.
"These claims are unsubstantiated and no evidence has been produced to support them.
"No formal AFL investigation will be undertaken in the absence of credible information or evidence."
The Lions were furious when the story first arose on Monday and have not backed down from their original statement.
"These claims from a 'self-confessed drug dealer' are completely unsubstantiated and do not deserve publicity," they said.
"We have no reason to believe the word of a 'self-confessed drug dealer', but if anyone, including The Courier-Mail, has any evidence with regards to this, or any other matter, it should be referred to either the AFL integrity unit or the Queensland Police.''
Earlier, Brisbane coach and former captain Michael Voss said he could not rule out the possibility that players used drugs during the period alleged by The Courier-Mail.
"They could have been (doing anything)," Voss told Triple M radio on Tuesday.
"I'm not naive enough to sit here and say that it hasn't happened.
"I couldn't say that with 100 per cent certainty."
Asked if he'd ever met Jason McGrath, Voss said: "Not that I can certainly recall.
"That's why we say they (the claims) are unsubstantiated.
"The names that have been thrown around I haven't even seen before.
"Speaking to some of my other teammates yesterday they don't know who he is either.
"But he might be familiar to some of our players at that stage of our careers, but he certainly wasn't to a majority of us."
Michael Whiting covers Brisbane Lions news for AFL.com.au. Follow him on Twitter: @AFL_mikewhiting
