The rider has been removed from the event with immediate effect
Manx Grand Prix competitor Alex Sinclair has been excluded from this year's event after returning a positive test for a 'recreational drug'.
In a statement, ACU Events Ltd. says this comes following a random drugs test carried out as part of the event's drug and alcohol screening protocols.
Sinclair's exclusion is with immediate effect.
ACU Events Ltd. adds: "The matter will be passed to the Auto-Cycle Union, the national governing body for motorcycle sport in Great Britain (less Northern Ireland). Sanctions for competitors caught doping can be a ban from ACU competitions for a minimum of two years.
"The Manx Grand Prix Races and ACU share a strict zero-tolerance policy for the presence of drugs and alcohol for officials and competitors during an event period."
UPDATE: At 4.45pm organisers issued a correction to the information released to the public today. They have confirmed Alex Sinclair recorded a 'non-negative' test result and not a 'positive' result as originally stated. You can find out more HERE.