A rising star of the horse-racing world, three-year-old sprinter End Assembly has tested positive to cocaine and risks being stripped of the biggest win of his promising career.

Trained in Toowoomba by Mark Currie, the undefeated star won the listed Gold Edition Plate in December, but tested positive to the illicit drug in both A and B post-race urine samples.

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The Queensland Racing Integrity Commission has confirmed it is investigating the matter, with a stewards inquiry set to begin next week.

“A Toowoomba-trained racehorse has tested positive to cocaine, following its win in a $200,000 feature race at Eagle Farm in December last year,” the commission said in a statement.

“The results of the post-race urine sample conducted by QRIC’s Racing Science Centre and Victoria’s Racing Analytical Services have returned positive to the banned illicit drug.

“QRIC stewards will hold an inquiry with the horse’s trainer early next week.”

If found guilty, connections to the horse face being stripped of the victory and all prize money.

End Assembly won his first two races in Toowoomba by a combined 12 lengths before winning the Gold Edition in the Queensland summer carnival.

It was reportedly well backed in that race and started as a $9 chance.