UK Athletics suspend Gareth Warburton and he will miss Commonwealth Games
The Welshman will now take no part in the Commonwealth Games, which begin in Glasgow on July 23.
UK Athletics have confirmed that Warburton has the opportunity to respond to the charges levelled against him.
Responding to the news, Warburton released a statement that read: "The news of this anti-doping rule violation has come as a great shock to me. From the outset, I would like to state that I have not knowingly taken any banned substance.
"As a professional athlete, I have always supported and have been an advocate of clean sport. Nothing has changed in this regard.
"However, I recognise that the responsibility for this situation lies with me and I'm committed to working with UK anti-doping and will fully cooperate in the legal process.
"I'd like to take this opportunity to wish the best to all my team-mates heading to the Commonwealth Games and apologise that I won't be able to join them as part of Team Wales."
Warburton finished fourth in the 800m at the last Commonwealth Games in Delhi and also represented Great Britain at the 2012 London Olympics.