Welsh Athletics has vowed to carry out an internal review after a second drugs scandal hit its team at the Commonwealth Games.
European 400 metres hurdles champion Rhys Williams, the co-captain of Wales' athletics squad in Glasgow, has been provisionally suspended and will miss the event after failing a drugs test.
The 30-year-old son of rugby union great JJ Williams becomes the second Welsh athlete to be forced out of the Games over an alleged doping offence , after 800m runner Gareth Warburton was withdrawn nine days ago.
He said he was "utterly devastated" by the news of his failed test and insisted, like Warburton, that he had never knowingly doped.
However, Welsh Athletics admitted it was "concerned" to see a second member of its team charged with committing an anti-doping rule violation.
The body said in a statement: "Rhys has the opportunity to respond to the charges against him and to have those charges determined at a full hearing before the national anti-doping panel.
"Welsh Athletics strongly supports clean sport and has established a comprehensive education programme for its athletes.
"Welsh Athletics is obviously concerned that this is the second anti-doping violation by a senior Welsh international athlete and will be conducting its own internal review."
Williams won the European title in Helsinki ahead of London 2012, having claimed silver and bronze at previous European Championships. He failed to gain selection for the Great Britain team for next month's Europeans in Zurich, though.
Williams, who also took bronze at the Commonwealth Games in Delhi four years ago, said he was shocked to test positive.
In a statement released through his management company Concept Sports Management, he said: " I am utterly devastated about the news of this anti-doping rule violation, which has come as a great shock to me. From the outset, I would strongly 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. 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 co-operate in the legal process.
"I'd like to take this opportunity to wish all the best to my team-mates at the Commonwealth Games. To be named co-team captain for the Welsh athletics team was a great honour and I am distraught that I won't be able to fulfil this role and join them as part of Team Wales. I wish them all well.
"Finally, in line with this process and until the hearing of the national anti-doping panel, I will not be making any further comment."
Welsh athletics chief executive Matt Newman said the news was "a massive blow for athletics in Wales" and "not something we ever envisaged".
He added to www.walesonline.co.uk: " The fact there have been two cases in a short space of time means it's not a coincidence.
"But at this stage we just hope we can back up what the athletes suspect is the source of the contamination."