In an interview with the BBC, the 24-year-old, who rode for Team Sky in 2013 and 2014, also said he had severe depression after independently using the controversial painkiller tramadol.

The injections contravene the International Cycling Union’s (UCI) "no-needle" policy, which Edmondson says he breached "two or three times a week" for about a month due to the pressure of his selection for a major race in 2014.

Team Sky say legal vitamins and a needle were found in Edmondson's room, but they decided against reporting the incident to the authorities as "there was no evidence of any anti-doping violation having taken place" and because they were concerned about his mental health.

They insist Edmondson had denied using them as he did not know how to use the needles.

Dr Steve Peters, Team Sky's then head of medicine, confirmed to the BBC that a member of Team Sky who lived with Edmondson had found "a needle and some vials" and had taken a photograph of the evidence.

Edmondson says he confessed to Team Sky at the time and accused senior management of a "cover-up".

In a wide-ranging interview, Edmondson told the BBC he traveled to Italy from his training base in Nice to buy a variety of legal vitamins and intravenous equipment and risked giving himself a heart attack by self-administering the medication secretly at night.

"In 2014, I was under a lot of pressure, not just from the team but from myself," he said.

"You want to renew your contract for one thing, and for me the bigger thing was not letting anyone down - this team had given me a chance by signing me and a bigger chance by letting me go to a Grand Tour [the Vuelta a España].

"I bought butterfly clips, the syringes, the carnitine [a supplement], folic acid, 'TAD' [a supplement], damiana compositum, and [vitamin] B12, and I'd just inject that two or three times a week maybe.

"Especially when I wanted to lose weight, I'd inject the carnitine more often because it was very effective."

Edmondson claims he told Team Sky's senior management he had self-injected at the time, but that there was a "cover-up".

"I think that would have meant a bigger admission for them," he said.

"They'd have had to say publicly a kid was injecting.

"Injecting anything's bad.

"It's not like they were banned substances but injecting is against the rules - to self-administer anything, I believe."

Dr Peters denied there had been any cover-up.

"Once you use that word you are saying there was an intent behind us to conceal and that was never the case," he said.

Asked whether Team Sky should have handled the case differently, Dr Peters said: "We could have reported it.

"We could have made a different decision.

"We'll never know in hindsight.

"I suppose if I'm looking at safety issues I did think there was a really big risk this lad would be pushed over the edge.

"I stand by my decision.

"I think I'd definitely have told them if I thought this young man was trying to cheat, but I don't think he was doing that."

The vitamins Edmondson bought are legal, but the UCI introduced rules in 2011 banning cyclists from using needles.

Edmondson also admitted to independently taking powerful opioid tramadol during the 2013 Tour of Britain.

Team Sky say this was given to him without their knowledge by the race doctor, as oppose to their own team doctor.

Tramadol has been blamed for causing crashes in cycling by making riders drowsy, and there are worries it may have addictive side-effects.

The World Anti-Doping Agency (WADA) have received calls from both UK Anti-Doping (UKAD) and the United States Anti-Doping Agency (USADA) to ban it.

"When you're young and you are facing some kind of depression and it might be linked to some sort of drug you are definitely in denial about what that problem is - I just saw it as the stress of doing that job and training hard," Edmondson added.

"I wouldn't have ever acknowledged that tramadol was doing that.

"It was a serious problem for me especially towards the end of 2014.

"I didn't leave the house for two months.

"It doesn't get much worse than that."

Earlier this week, Team Sky revealed in a letter to the Culture, Media and Sport Select Committee that its former doctor Richard Freeman purchased fluimucil in a Swiss pharmacy just two months before it was transported to Sir Bradley Wiggins.

British Cycling and Team Sky are currently at the centre of a UKAD investigation into a "mystery package" delivered for Sir Bradley at the 2011 Criterium du Dauphine.

It is claimed that the package contained fluimucil, a decongestant that is used to treat coughs and sore throats, but elements of the story are still unclear.