Australian police have raided the stables of one of the nation's leading horse trainers, arresting three men over a probe into alleged racing fraud.
The men were held for questioning in Victoria on Wednesday, police said, adding that no charges had been laid.
Local media named one man in custody as Darren Weir, the owner of the stables.
Mr Weir trained Prince of Penzance, the horse ridden by trailblazing jockey Michelle Payne to win Australia's top race, the Melbourne Cup, in 2015.
Police said the three men arrested would be questioned over "sporting integrity matters".
They include suspected offences such as obtaining financial advantage by deception, and engaging in conduct that corrupts or would corrupt a betting outcome.
"Today's warrants show that Victoria Police will investigate allegations of corruption in sport and racing," Assistant Commissioner Neil Paterson told reporters.
He would not elaborate on the nature of the allegations, but said they would be revealed "in the fullness of time".
Racing Victoria, the sport's local governing body, said the arrests followed a joint investigation with police into the "activities of licensed persons" in the industry.
"Racing Victoria is committed to maintaining the highest integrity standards in our sport," a representative said.
Police said they had seized a firearm, taser and other items from the stables in the cities of Warrnambool and Ballarat.
A veteran of Australia's racing industry, Mr Weir holds the national record for the most wins by a trainer in a season.
He has hundreds of horses in his stables, and is one of the largest employers in the sport in Australia, local media reported.
The industry has previously been marred by allegations of corruption and cheating.
Last year, five trainers at a stable in Victoria were banned from the sport after they were found guilty of doping horses before races.