Sofia, Bulgaria: Bulgarian athlete Silvia Danekova confirmed Friday that she had failed a doping test at the Olympics in Rio, with Bulgarian television saying she tested positive for blood booster EPO.

‘I am not guilty, I have done nothing wrong. Four tests were done, three of them were negative. We found out that my fourth test was positive,’ said the 33-year-old, who has been provisionally suspended.

‘The shock for me is unbelievable,’ she told Bulgarian public television channel BNT. ‘The only explanation can be food additives that I have been taking.’

Bulgarian television reported that a B sample for Danekova, who came 14th in the steeplechase in the World Championships in Moscow in 2013, was also positive for EPO.

The news came ahead of the start of the athletics in Rio, with three gold medals up for grabs at the Olympic stadium including in the women’s 10,000m race.

After a year of drug scandals involving Russia, Kenya and other nations, track and field is looking for its stars to restore trust in the sport.

All but one of Russia’s track and field athletes were banned from Rio after a World Anti-Doping Agency (WADA) report last year alleged a ‘state-sponsored’ doping conspiracy across Russian sport.

Kenya on Thursday withdrew a second athletics coach from the Rio Olympics in five days over a doping cheat bid.

The International Olympic Committee (IOC) said it had launched disciplinary proceedings against the coach who media reports said had impersonated an athlete for a doping test.

The official has been named in media reports as sprint coach John Anzrah.

Ex-communist Bulgaria — which has produced 36 Olympic weightlifting medallists — had all its lifters excluded from Rio in August after 11 athletes tested positive for the banned drug stanozolol in March.