Irish distance runner Cathal Lombard is set to miss the Olympics after testing positive for blood-boosting drug EPO.
Athletics has been dogged by the drugs issue in recent months
Lombard had qualified to compete in the 5,000m and 10,000m in Athens.
"The Irish sports council have come across an EPO positive for Cathal Lombard," said Irish Olympic press attaché Jack McGouran.
"He will be given 24 hours to come up with a response and if he doesn't do that he will not be in the Irish Olympic team."
Athletics Ireland said that a further statement would be made following the athlete's formal response to the alleged offence.
Doping violations involving EPO usually lead to a two-year ban from the sport.
Lombard made a major breakthrough in the last two years and in April bettered the previous Irish 10,000m record by over 13 seconds with a clocking of 27:33.53.