Irish swimmer Grainne Murphy revealed that she had little choice but to withdraw from the London 2012 Olympics on medical grounds.

Murphy had been due to take part in the 800m freestyle event on Thursday, but has dramatically pulled out as she is still suffering from the effects of a case of glandular fever.

The Limerick-based Murphy was hit with the viral illness last March, and despite her best efforts, the after effects have prevented her from competing.

She said: "I tried to keep it very low key, I’m not really a person that likes to say these things out. It was very difficult to come to terms with it myself so it took me a while to adjust."

Murphy who had already pulled out of the 200m freestyle, was hoping to be fit for the 800m, but after she finished last in her 400m heat, it became apparent that she was well below her best.

"I came here to compete as best I can, but right now my ability isn’t up to where I want it to be" - Grainne Murphy

"After swimming the 400m and speaking to everybody, getting advice from, (Chef de Mission) Sonia (O’Sullivan), speaking to Peter Banks (Swim Ireland performance director), I think this is the best decision for me," she said.

Murphy insisted that she has no regrets in going to London and that she did everything she possibly could to ensure she would be ready for the Olympics.

She said: “I prepared everything I could coming up the Games, I did my recovery, I worked very well with [my coach] Ronald [Claes] and the support team, so we did everything we possibly could to get here.

"I think after swimming the 400m on Sunday I now realise that I need to recover and get better for next season and do the best I can."

Peter Banks insisted that Murphy will continue to have the full support of Team Ireland, saying: "We obviously want to support Grainne, want to make sure that she’s in the right place and that all the team members and staff around her are supporting her and that we can give her any kind of help and support she needs."