Prenoveau, 51, tested positive for the presence of hydrochlorothiazide and its related metabolites as a result of an in-competition urine sample he provided on November 5 in 2016.

The testing took place at the USA Curling wheelchair national team trials in Wausau in Wisconsin.

Hydrochlorothiazide comes under the category of diuretics and masking agents and is prohibited under the World Anti-Doping Code. 

"After a thorough review of the case, including the examination of medical records provided by the athlete, USADA determined that Prenoveau’s positive test was caused by a prescribed medication that he was using in a therapeutic dose under the care of a physician," read a statement from USADA.

"USADA has since granted Prenoveau a Therapeutic Use Exemption (TUE) authorising his continued use of this medication."

In addition to accepting a public warning, Prenoveau has been disqualified from all competitive results obtained on the date his positive sample was collected.

Prenoveau has cerebral palsy. 

He was an alternate on America's team at both the 2005 and 2008 World Wheelchair Championships.

The the 2017 World Wheelchair Curling Championships are currently taking place in Gangneung in South Korea.

Prenoveau was not scheduled to compete for the US with Stephen Emt, Kirk Black, Jimmy Joseph, Penny Greely and Justin Marshall forming their squad.

The WCF had nothing further to add to the USADA statement comment,while USA Curling reaffirmed its intention to follow anti-doping laws closely.

"USA Curling regrets that wheelchair curler Robert Prenoveau did not request a TUE for a prescribed medication to treat a medical condition in advance of competition," said USA Curling's director of communications, Terry L. Davis.

"Mr Prenoveau has accepted his warning and has worked with USADA to receive the proper TUE.

"USA Curling and its athletes are committed to following the USADA and WADA guidelines to ensure that our athletes compete clean."