Sir Mo, the Olympic 5,000 and 10,000 metres champion at London 2012 and Rio 2016, received an injection of L-carnitine before racing in the 2014 London Marathon.

Dr Robin Chakraverty, now lead performance doctor of the England men's football team, said the substance was provided to aid the runner’s performance but that the amount was comfortably within the levels permitted by the World Anti-Doping Agency (WADA).

Chakraverty said he administered 13.5 millilitres of L-carnitine, of which injections of more than 50ml within a six-hour time frame are prohibited.

He is thought to have carried out the treatment on the order of Sir Mo's American coach Alberto Salazar.

Asked by Culture, Media and Sport Select Committee chair Damian Collins why it was not recorded on the athlete's records, Chakraverty put it down to being an example of a "lapse".

"I'm a doctor in a lead sport - I was responsible for the healthcare of 140 athletes on a programme," said Chakraverty, who was questioned alongside UK Athletics head of endurance Barry Fudge and former UK Athletics medical officer John Rogers.

"Previously we'd had four doctors working for UK Athletics and in my time we had two doctors and one of them wasn’t working full-time.

"So it’s an immensely busy job and when you’re in your base, which for me was Loughborough, and you’re in your clinic room, which is in the training centre, and an athlete comes in, or a patient comes in, and you have your access to your computer, I think recording is very good.

"Where we have had lapses is when you’re on the road, when you’re travelling, and that’s probably the unique thing about this role that not all our athletes train in one area. 

"When you are constantly on call for athletes you travel to those athletes and if you don’t record it straight away, which I didn’t in this case, then it can get forgotten because you’ve got all these other things.

"However, having said that, that’s just the scenario you’re in - it’s not an excuse, it’s just giving you context.

"The [UK Athletics] Performance Oversight Committee sat and one of their recommendations was upping our level of record keeping and our record keeping did improve during my tenure as chief medical officer and continues to improve."

Salazar and the Nike Oregon Project he heads is currently at the centre of a United States Anti-Doping Agency (USADA) investigation into doping and unethical practices.

The Times reported last month that Sir Mo was among a group of athletes at the Nike Oregon Project told to stop taking the supplement in 2013.

A copy of a USADA report, compiled in 2016 and leaked by hacking group Fancy Bears', alleged that athletes were given potentially harmful legal prescription drugs when they had no medical need.

Rogers visited a training camp held in France in 2011 and told the Culture, Media and Sport Select Committee that Salazar's understanding of sports medicine and science was then better than any coach he had previously worked with.

"We had several conversations there and he was very open and transparent about the sports medicine practices he was using," he said.

"There was no concern there were any WADA rules being broken.

"There were some medical concerns around possible side-effects from some of the strategies they were using and it was important I shared that in terms of the continuity of care."

The USADA report also claimed that Salazar boasted about the effects of L-carnitine to disgraced cyclist Lance Armstrong, who was stripped of his seven Tour de France titles after admitting doping. 

Salazar and Sir Mo strongly deny any wrongdoing and claim the injection, which USADA has called an infusion, did not break any rules.

Chakraverty's admission today comes less than two months after UK Anti-Doping (UKAD) chief executive Nicole Sapstead told the Culture, Media and Sport Select Committee that there have been no records kept of the "mystery package" delivered for cyclist Sir Bradley Wiggins at the 2011 Criterium du Dauphine.

British Cycling is at the centre of a UKAD investigation regarding the package, which former Team Sky doctor Richard Freeman received on behalf of Sir Bradley on the last day of the traditional build-up race for the Tour de France.

Sapstead said Freeman had a laptop containing medical records stolen in 2014 and that "no-one has any recognition of what was in the package". 

Ed Warner, chair of UK Athletics, was also questioned today alongside UK Sport chief executive Liz Nicholl and described both cases, involving Sir Mo and Sir Bradley, as "inexcusable". 

"If my child went to see the GP and he or she failed to record something on their records it would be as inexcusable as not recording something on Mo Farah’s records," he added.

"So I think they’re of equal concern and improving medical record keeping isn’t having a gold-plated standard for a gold-plated athlete.

"It’s having the same gold-plated standard for all athletes.

"That has to be the ambition."

Team Sky boss Sir Dave Brailsford revealed to the Culture, Media and Sport Select Committee in December that he had been told that fluimucil, a decongestant that is used to treat coughs and sore throats, was delivered to Sir Bradley.

Sapstead confirmed that UKAD had spoken about the matter to Sir Bradley, whose "recollection was that he was treated with fluimucil" on the evening of June 12, 2011. 

Warner said UK Athletics should not be tarred with the same brush as British Cycling and Team Sky with regard to record-keeping and insisted his organisation was keen to centralise its records and now handles all of Sir Mo's medical care.

"There was a period of a few months in which we allowed Mo to go to Oregon and be treated by a local GP over in America, and we were observing his medical care from afar," he added.

"A decision was taken that we had to make sure we were in control of all medical interventions where Mo was concerned. 

"That should always be the case for funded athletes."

Collins said at the beginning of the hearing that the MPs' final report into anti-doping would now not be published until after the UK General Election, which is scheduled for June 8.