West, who has finished runner-up in the last two Moto2 races, gave a sample back at Le Mans in May which was found to contain traces of a prohibited substance.
Organising body FIM, the Federation Internationale de Motorcyclisme, said that West's sample contained Methylhexaneamine, on its list of banned 'specified stimulants.'
As a result the FIM has disqualified the 31-year-old Australian from the French Grand Prix results, and has also banned him for one month from competing in an FIM-sanctioned or FIM-affiliated race, effectively immediately.
West has five days to appeal the decision.
Methylhexaneamine is considered a stimulant as it increases heart rate and blood pressure, and can be found in training supplements - although it isn't always identified on the product.
Should West's appeal prove unsuccessful, he will miss the Moto2 finale at Valencia next weekend.
- Sports & Recreation