The duo have been disqualified from the event, held in Normandy, following the horse’s positive test for Hydroxyethylpromazine sulfoxide, a metabolite of the sedative Acepromazine, a substance used regularly to treat horses but is on the prohibited controlled medication list.

The sample in question was taken during the dressage day of the World Equestrian Games, on August 29, and it was revealed in September that the horse had tested positive.

The French team, which also included Jean Teulere, Cédric Lyard and Pascal Leroy, had finished fourth at the competition, which was enough to earn them a place at Rio 2016, but that has now been removed as if riders or horses test positive, the whole team are liable for punishment.

However, they could still compete in Rio if they qualify through the 2015 European Eventing Championships, due to be staged at Blair Castle in Scotland from September 10 to 13, or through the FEI individual rankings system.

They were found to be in breach of the FEI’s Equine Anti-Doping and Controlled Medication Regulations and could come under further sanction, although any additional punishment has yet to be announced by the sport's governing body.

A separate case involving the French rider was dismissed by the FEI earlier this month after a B sample on Bingo S, a borrowed horse ridden by Livio at an event in Thailand last November, failed to back up the initial positive result.

The news will come as a blow to the French team and their spot at Rio 2016 has been taken by Canada, who had originally finished seventh in Normandy.

Brazil automatically qualify as host nation of the 2016 Games and they will be joined by Germany, Great Britain, the Netherlands, Australia and Ireland.

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September 2014: France face disqualification from Rio 2016 eventing after horse fails test