Rio 2016: Irish boxer Michael O'Reilly becomes first athlete to fail drugs test

The 23-year-old middleweight may yet ask for his 'B' sample to be tested

O'Reilly won gold at the European Games in 2015 (Getty)

Michael O’Reilly, the Irish boxer, has become the first athlete at the Rio Olympics to test positive for a banned substance.

The Portaloise-born middleweight failed a drugs test administered by the Irish Sports Council prior to flying to Brazil with the rest of the Republic of Ireland squad.

O’Reilly has been provisionally suspended from competing at the Games, which officially start on Friday, and is reportedly planning to challenge the decision, according to RTÉ.

The 23-year-old, who won gold at the European Games in 2015, can request to have his ‘B’ sample tested but, under Irish anti-doping regulations, he cannot participate until an investigation has been carried out.

O’Reilly was scheduled to take to the ring next Friday, having received a bye to last-16 of men’s middleweight competition.

In the hours after suspension was confirmed, O’Reilly appeared to suggest that he would fight as scheduled, writing on Twitter: “Box on the 12th in the last 16 against the winner of Mexico or Iraq.....”

The tweet was subsequently deleted.