Heartbroken Fiona Doyle could not hide her dismay and frustration after seeing Russian Yulia Efimova qualify from her 100m breast stroke heat, saying: "Cheaters are cheaters."

Doyle finished eighth in Heat 5 at the Olympic Aquatic Centre, and 20th overall, 0.26 seconds outside the top 16 and thus being denied a place in the semi-finals. 

The Limerick woman admitted she was "devastated" afterwards, with Efimova's presence rubbing salt into the wounds.

Efimova was added to the 271 Russian athletes eligible to compete in Brazil at the very last minute; she had appealed to the Court of Arbitration for Sport (CAS) after the International Olympic Committee initially banned all Russian competitors who had previously tested positive for doping.

Efimova was banned between October 2013 and February 2015 after testing positive for traces of the anabolic steroid DHEA. She was also briefly suspended after testing positive for meldonium this year, but cleared in July.

Meldonium was added to the World Anti-Doping Agency's list of banned substances from 1 January, but some positive tests were later overturned after WADA said there was a lack of clear scientific evidence about how long it takes for the drug to be excreted from the body. 

Efimova, the world champion at the distance, clocked 1 minute 5.79 seconds, a hundredth of a second behind American Lilly King whose compatriot Katie Meili was third in 1:06.00 with holder Ruta Meilutyte of Lithuania fourth in 1:06.35. 

Some jeers rang out in the Olympic Aquatics Stadium after Efimova's heat.

“Cheaters are cheaters,” Doyle told the Irish Times, noting Efimova's previous history of testing positive. “It’s like FINA (Fédération internationale de natation - the international swimming federation) keep going back on their word, and the IOC (International Olympic Committee) keep going back on their word.

“FINA caved in to Putin, and that’s just not fair on the rest of the athletes who are clean. Who are you supposed to trust now? They have signs all over the village saying we are a clean sport, and it’s not. And I just don’t think that’s fair.”

Doyle choked back tears as she reflected on a brave performance. 

She started strongly, keeping with the pace for the first 50m, turning in third, but she slowed to the finish and ultimately missed out.

"I have to just look at the footage and see what I did and see what I can do better," Doyle added. "Tomorrow's a new day. It's been fantastic.

"I've loved every minute of it. I felt absolutely fantastic in the warm-up, I felt better better than I've ever felt before in my whole life, so to not progress, I'm devastated."