The Brisbane Broncos have fined Karmichael Hunt, Darius Boyd and Sam Thaiday $20,000 each for bringing the club into disrepute, despite police finding there was insufficient evidence to charge the NRL stars with sexual assault.

A team of 12 police investigators probed allegations of sexual assault on a 24-year-old woman in a Brisbane nightclub toilet on September 13.

Police cleared the three Queensland State of Origin representatives over the alleged assault and also declined to lay charges over a subsequent drug allegation probe.

But Broncos chief executive Bruno Cullen said the club had fined the players $20,000 each, and would force them to undergo behaviour counselling.

He said their actions in relation to the sexual assault allegations breached the club's code of conduct and also their NRL contracts by damaging the reputation of the game.

Cullen said the three players would also miss out on third-party sponsorships, costing them up to $60,000.

"It is said that professional footballers can accept any fine, but I can tell you now under the financial conditions of today a $20,000 fine is a fair whack," he said.

"The players will be subject to sanctions with regard to third-party deals with sponsors and I can guarantee that in at least two cases that will cost the players $60,000."

Cullen said an internal investigation conducted by the club concluded that the players should not have been in that position in the first place.

"I think they were very, very stupid in putting themselves in a position that led into what eventuated over the last six weeks," he said.

Cullen said the $20,000 fines would be spent on counselling and any money left over would be donated to charity.

Police Deputy Commissioner Ian Stewart said the woman who made the allegations had accepted the findings and had been offered support.

Mr Stewart said barrister Tim Carmody, who was last month asked by police to review evidence, agreed with the findings.

During the sexual assault investigation, police discovered footage of alleged drug use on a mobile phone video camera.

But Mr Stewart told reporters there was insufficient evidence to lay any drug charges.

He said police would not be handing over the material relating to the drug investigation to Broncos club officials as such a move was unwarranted in the circumstances.

Mr Stewart said police believed the explanations given in the drug-related incident, which allegedly involved two unnamed Broncos men and two members of other Brisbane football clubs.

Cullen said the two players caught up in the drug investigation would not be punished.

"One particular newspaper said a Broncos player was under investigation for taking drugs," he said.

"There was some Broncos players associated with the action of another party in being present. But at no time was that Broncos player under investigation for taking drugs."

Cullen said the three Broncos players would issue a public apology.

The entire Broncos squad was on notice over behaviour standards, he said.

"These are not good times, they are very difficult times to handle," Cullen said.

NRL chief executive David Gallop said the Broncos had kept them informed throughout the investigation.

"The action they have taken is significant," Gallop said.

"It is important that clubs use the education programs that are available, as well as meaningful penalties in these cases, and it would appear that the Broncos have done that."

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