Several racing figures have been interviewed and phone records searched as part of an investigation sparked by the alleged raceday treatment of a Robert Smerdon-trained horse.
The investigation reportedly involves several stables, training figures and racing administrators.
Smerdon is being investigated over the alleged raceday treatment of the mare Lovani on Turnbull Stakes day on October 7.
Racing Victoria's integrity unit has since interviewed a number of people and examined a number of mobile phones, amid reports about the alleged use of coded text messages.
Racing Victoria chief steward Terry Bailey confirmed the investigation.
"We're dealing with an alleged race day treatment on Turnbull Stakes day," he said on Thursday.
"It's required us to interview a number of people and that process is still going on.
"We don't really want to make any comment until that process has finished.
"The investigation itself's not far from over."
Bailey would not go into details about the case, which has been the subject of several media reports on VRC Oaks day.
"A fair bit of time elapsed before we started carrying out further investigations and further interviews," he said.
"As soon as we started interviewing people then the innuendo and the gossip starts. We can't control that."
Lovani was scratched from the final race at Flemington on October 7, the Paris Lane Stakes, after Racing Victoria stewards suspected the mare had been treated following her arrival on course.
At the time Bailey said the allegation involved an oral administration, not an injection.
Smerdon and his float truck driver were interviewed by stewards on the day.
RV chief executive Giles Thompson said he would not comment on an ongoing investigation.
"The important thing that we have in racing is that we have fair racing and that all participants get a chance to engage in racing on a fair basis," he said.
"I'm not worried about it. We will investigate and prosecute as appropriate on any particular matter."
Victorian Racing Minister Martin Pakula would not comment other than to say the matter was under active investigation by RV stewards and its integrity department.
"I have every confidence in Mr Bailey and his team and I know that they will conduct a thorough investigation without fear or favour," Pakula said.