Rhys Williams, Wales' 400 metres hurdles champion, has been provisionally suspended after being charged with an anti-doping violation.
The 30-year-old, the son of rugby union great JJ Williams, becomes the second Welsh athlete to be forced out of the Commonwealth Games over an alleged anti-doping violation after 800m runner Gareth Warburton.
Welsh Athletics said in a statement: "Welsh Athletics can confirm the provisional suspension of Rhys Williams after being charged with committing an anti-doping rule violation under the IAAF Anti-Doping Rules.
"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.
"Welsh Athletics will not be making any further comment."
Williams, who was the co-captain of the Welsh athletics team in Glasgow, won the European title in Helsinki ahead of London 2012.
He also took bronze at the Commonwealth Games in Delhi four years ago.
Williams, who failed to gain selection for the Great Britain team for next month's European Championships in Zurich, said he was "absolutely devastated" by the news of his failed test and insisted he had never knowingly doped.
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."