Farah posted the statement on his Facebook page to protest his innocence after a fortnight that has seen his coach Alberto Salazar and training partner Galen Rupp accused of doping, and in which his own two missed tests ahead of London 2012 have been used to drum up suspicion.
"I have never taken performance enhancing drugs in my life and I never will," Farah said in his statement.
"Over the course of my career I have taken hundreds of drugs tests and every single one has been negative.
In defence of Mo Farah
"I’ve fully explained the only two tests in my career that I have ever missed, which the authorities understood, and there was never any suggestion that these were anything more than simple mistakes.
"The last two weeks have been the toughest of my life – with rumours and speculation about me that are completely false – and the impact this has had on my family and friends has left me angry, frustrated and upset.
"In particular, the media pressure on my young family and my wife, who is 5 months pregnant, is extremely painful, especially as I’m away training for some important races.
The last two weeks have been the toughest of my life – with rumours and speculation about me that are completely false
"As I made clear, I went to Portland to speak to Alberto Salazar and demand answers. He reassured me that the claims are false and that he will soon be providing evidence to make that clear.
"Until then I will not be commenting further on the allegations.
"I would like to take this opportunity to thank my fans, family, friends and teammates for all the great support they have provided over the last few days and hope that I will now be allowed to focus on my training and winning medals for my country."
[BLOG: In defence of Mo Farah]
Farah's denial comes a day after the Daily Mail revealed that Mo Farah had missed two doping tests in the run-up to the London 2012 Olympics.
On one of those occasions, Farah argued that he had not heard the doorbell at his house in Teddington.
However, Friday morning's edition of The Sun claimed that doping investigators, "rang Mo Farah's doorbell for an HOUR without reply while the athlete was inside".
The paper quoted the legal director of UK Anti-Doping, Graham Arthur, explaining that to do so is standard practice:
"Doping control officers are required to make reasonable efforts to locate the athlete," he said.
"That includes ringing the doorbell every 10-15 minutes or so, knocking and staying there for the full hour, even longer on the off-chance that the athlete is running late or is trying to make it back in time.
"A missed test doesn’t mean that somebody has deliberately not opened the door, or has hidden in the bathroom for an hour. If we thought that had happened, we would take action against them for evasion. That carries a straight four-year ban."
Mo Farah accused of missing two doping tests before London 2012
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