Police swooped on Leven bus depot late on Monday night.
One witness described how workers cleaning the buses were told to leave so officers with sniffer dogs could search the vehicles.
A spokeswoman for Stagecoach East Scotland said: “There was heavy police presence at Leven bus depot around 11pm last night due to searching for a person of interest.
“It is thought the said person may have been sleeping on board one of our buses, however, police and Stagecoach staff searched the area and no one was found.
“Any additional information will be passed onto the police to further their investigation.”
