Sydney - A Melbourne Cup-winning horse trainer was arrested on Wednesday over corruption allegations, local media reported, following a police investigation into the use of electric shock devices to gain a racing edge.
Police arrested three men on Wednesday morning after raids on several rural properties which netted an unregistered firearm, some cocaine and four taser-like devices - known in the industry as jiggers.
The banned electronic devices have been used by jockeys during races and training in order to shock horses into running faster.
"The allegation is that they (jiggers) may be used against a horse... with the aim of improving their performance on a particular race day," Victoria Police assistant commissioner Neil Paterson told reporters.
The names of the men - aged 26, 38 and 48 - were not released by police but the 48-year-old was widely reported by Australian media to be horse trainer Darren Weir.
A veteran of the sport, Weir is renowned for training Prince of Penzance, which female jockey Michelle Payne rode to victory in the 2015 Melbourne Cup.
Police later released all three from custody pending further investigation.
The men were questioned as part of an inquiry stretching back to August that includes allegations of bet rigging and animal cruelty offences.
"The investigation isn't just about the use of jiggers. It goes to the heart of the offences that relate to the sporting integrity, so that's corrupting betting outcomes," Paterson said.
Racing Victoria said it had been investigating several people and had sought the help of police.
"What is vital for the image of racing is that the integrity of racing is maintained," Racing Victoria chief executive Giles Thompson told reporters.
"To do that, you have to investigate. We invest a huge amount of resources in our integrity team, and occasionally, you end up with issues like this."