Uganda's wildlife authority has suspended 11 of its employees over the suspected sale of fake gorilla permits.
The government agency, which sells passes allowing tourists to see gorillas up close, said it had found anomalies in its online transactions.
Safari companies say a permit currently costs about $700 (£575) per person per trek - and a limited number are offered each year.
According to Uganda's private Daily Monitor newspaper, auditors noticed that the number of visitors at Mgahinga and Bwindi national parks did not tally with revenue collected.
Bashir Hang, spokesperson from the Uganda Wildlife Authority (UWA), said the possibility that staff and tour operators had worked together to commit fraud was being investigated.
The agency added it had not yet established how much money it had lost to the suspected fraud.
A number of UWA bosses were set to be questioned about the scandal, state-run New Vision newspaper said.
Gorillas generate significant tourism revenue for Uganda, and some of the money goes towards wildlife conservation efforts.