Horses are already being moved from Darren Weir's stables as the trainer fights for his career after being charged with possessing electronic devices known as jiggers, which are outlawed in racing.

The champion trainer, who has more than 600 horses on his books, was charged by Racing Victoria stewards on Friday, two days after they and officers from the Victoria Police sports integrity unit raided his stables at Ballarat and Warrnambool.

As well as being charged over the jiggers, Weir and his Warrnambool stable foreman, licensed trainer Jarrod McLean, have been charged with failing to answer stewards' questions at the opening of the inquiry on Thursday.

After charging Weir on Friday, stewards also opened a show-cause hearing, asking him and McLean why their nominations should not be refused.

They then scratched the trainers' runners from race meetings on Friday night, Saturday, Sunday and Monday when the show-cause hearing will resume.

Among the horses withdrawn is high-profile sprinter Nature Strip, formerly the odds-on favourite for the Listed W J Adams Stakes at Caulfield on Saturday, who will reportedly join the Chris Waller stable.

Victoria Derby winner Extra Brut is expected to go to Ciaron Maher Racing at Caulfield while another Group One winner Brave Smash will head to Kris Lees at Newcastle.

Lindsay Park, headed by David Hayes, will receive Thousand Guineas winner, Amphitrite.

McLean trained his first Group One winner in November but that horse, Trap For Fools, will go to Robert Hickmott.

Most of the horses being transferred are well into preparations for autumn carnival racing, with Extra Brut one of those scratched from Caulfield.

RV's head of integrity, Jamie Stier, said stewards took the step to scratch the horses from the weekend's meetings given the nature of the charges.

"The stewards are concerned about the seriousness of the threat posed by Mr Weir's and Mr McLean's alleged possession of an electronic apparatus. This is a significant issue in terms of animal welfare and racing integrity," he said in a statement.

"The investigation has caused considerable public concern, and has generated considerable negative publicity, bringing into question the impact on the image, interests and integrity of racing of Mr Weir and Mr McLean's continued participation in racing pending the hearing of the charges."

A jigger is usually a small electrical device used in conjunction with a whip to try to stimulate a horse to run faster.

It is used in training and the action is then simulated on race day so the horse believes it is about to be shocked again.

Giles Thompson, chief executive of RV, said he sympathised with the owners but that "the integrity of the sport and its reputation must come first.

"I'm also aware that there will be a number of hard-working stable staff that will be concerned about what this may mean for their future," he said.

"Our Participant Wellbeing team has reached out to them offering a range of support services."

Weir, a five-time Melbourne premier trainer and the winner of the 2015 Melbourne Cup with Prince Of Penzance, has more than 600 horses on his books and employs around 150 people in his stables.

A former country trainer, Weir has amassed more than 3500 winners.