Leading trainer Peter Moody is facing a stewards investigation after one of his horses returned a high level of cobalt in a Group One race during the spring carnival.

A post-race urine sample taken from Lidari after his second placing in the Turnbull Stakes in October contained cobalt at a concentration in excess of allowable threshold of 200 micrograms per litre in urine.

Moody released a statement on Tuesday night saying he was mystified by the result and would co-operate with racing authorities.

"I am devastated to be informed by Racing Victoria Stewards that one of my runners has tested positive to a banned substance during the 2014 spring carnival," Moody said.

"I have no knowledge or understanding as to how this could occur and will work with the Racing Victoria Integrity Services Department to bring this matter to a conclusion as soon as possible.

"I take great pride in my role in thoroughbred racing in Victoria and strive to manage my business and support my wonderful group of owners and staff with the highest levels of honesty and professionalism.

"I will continue to pursue this goal over the next few months and do everything possible to clear my name."

A Racing Victoria stewards' release said the sample was tested at the Chem Centre in Western Australia and was confirmed by the Hong Kong Jockey Club laboratory.

Cobalt is an essential mineral nutrient which affects multiple body systems and is toxic at high dosages.

Low levels can be attributed to natural occurrence and feed supplements which prompted the introduction of the 200mcg/L threshold last year.

Moody, trainer of the now-retired unbeaten champion Black Caviar, has won four Melbourne trainers' premierships.

He brought up his 100th winner for the 2014/15 racing season on Monday.