Apprentice Mitch Aitken has been suspended for three weeks on a misconduct charge at Flemington.

He was also fined $500 for failing to ride at his declared riding weight for Saturday's meeting, where he had two rides.

Aitken was charged by Racing Victoria stewards following his second ride aboard Credible Witness in the Flemington Event Staff Handicap.

It was established Aitken had weighed out in a pair of lighter riding boots before changing them before the race.

Robert Cram, steward in charge of Saturday's meeting, said there were two specifics to Aitken's misconduct charge.

"One was of lying to stewards and one of disobeying a stewards directive," Cram said.

Aitken allegedly lied to steward Corrie Waller, who asked Aitken if the boots he was wearing were the ones he had weighed out in, while he disobeyed an earlier instruction to ride in those boots he weighed out in.

Aitken can return to riding on August 12.