Andrew Bree last night said he "would never cheat" and bring shame upon the sport of swimming.
In an exclusive interview with the Belfast Telegraph Bree said he was left "shocked" after swimming's world governing body FINA informed him he had tested positive for a banned substance.
The test was carried out during the European short course championships in Debrecen, Hungary in December when Bree used a Vick's nasal inhaler.
It is understood that the inhaler contained the substance lev-met amphetamine, which is located in the American version of the inhaler but not the UK version of the Vick's decongestive.
Bree said: "I just can't believe this, I'm totally shocked by it. I consider myself a role model for up and coming Irish swimmers and I would never do anything to blemish that or to bring shame on the sport.
"I want to see Irish swimming progress and the last thing I would do is cheat. I'm tested all the time because I'm a top ranked FINA swimmer and I've never had a problem. The next step is for me to clear my name so I can concentrate on Beijing."
Dad Barney was equally stunned by the positive test but is adamant that they will move quickly to have the unfortunate incident resolved.
Bree Snr stated: "We believe that this negative test is the result of Andrew unwittingly taking a stimulant contained within an over-the-counter decongestant. Andrew has never knowingly taken a banned substance and abhors the use of performance enhancing drugs. He will move to clear his name as quickly as possible so that he can continue preparations for the Beijing Olympics."
Bree's case mirrors that of British skier Alain Baxter who tested positive for the same substance after using an inhaler, having claimed bronze at the Winter Olympics in 2002.
The Scot appealed to the Court of Arbitration for Sport who judged that he was a "sincere and honest man who did not gain a competitive advantage despite the trace of lev-methamphetamine in his system."
World governing body FINA's rules suggest that Bree has a strong case to be allowed to continue competing as rule DC 10.3 states that "The Prohibited List may identify specified substances which are particularly susceptible to unintentional anti-doping rules violations because of their general availability in medicinal products or which are less likely to be successfully abused as doping agents.
"Where a Competitor can establish that the use of such a specified substance was not intended to enhance sport performance, the period of Ineligibility found in DC 10.2 shall be replaced with the following: First violation: At a minimum, a warning and reprimand and no period of Ineligibility from future Competitions, and at a maximum, one year's ineligibility."
It would be very harsh if the Helen's Bay man were to receive the maximum penalty as he has been a true ambassador for the sport and has clearly been caught out by substance which is of no consequence to a swimmer's performance.
Meanwhile, the veteran of British swimming Mark Foster qualified for the Olympics yesterday with a stunning display at the British trials in Sheffield.
The zip on Foster's swimsuit popped just before the start of the 50m freestyle final so he had to strip off and compete in the bottoms but it certainly didn't impede him as he led from the start to touch in 22.30 secs ahead of national record holder Simon Burnett.