Gareth Warburton and Rhys Williams say they are not cheats

Gareth Warburton and Rhys Williams say they are not cheats after being banned for failing drugs tests.

The Welsh athletes were "at fault or negligent" but had not knowingly taken anything containing the prohibited substances, says an official national anti-doping report published on Monday.

Williams, 30, was banned for four months and Warburton, 31, for six.

Warburton said: "I'm not a cheat. I'm a clean athlete. It's a contaminated substance case."

The independent tribunal found neither athlete took enough advice before consuming Mountain Fuel supplements, some of which were contaminated with an anabolic steroid.

Both athletes, who have now served their bans, have urged other athletes not to take sporting supplements after their experience with the contaminated blackcurrant-flavour energy drink.

"My advice is not to take supplements at all and if you do take them, do the right checks," said Warburton, who vowed to never again use such products.

"There's no way of knowing 100% that they're safe so if you're not 100% sure, don't take them."

Asked if he felt his punishment was fair, Warburton replied: "Yeah, I think it is."

Warburton says he and Williams were "just unlucky" and that his ban has been accompanied by a £10,000 financial loss, plus sponsors withdrawing their support.

He added: "Emotionally it's cost a lot... but I think I've come out as a better person."

Williams echoed Warburton when he said: "Parents will probably like it, it'll save them money, but don't touch supplements."

Former European 400m hurdles champion Williams added the case had cost him about £100,000 and claimed he should have been exonerated.

"I should have received [a ban of] nothing because I've done nothing wrong," said Williams.

"And you look at the facts and figures and you can see that."

He added he was "baffled" by it all and said athlete education was not good enough if he and Warburton could be caught out.

Williams says he looked at relevant information before using the supplement, saying: "I did all these checks."

The official report countered Williams' assertion, saying: "The enquiries he made of DF [Mountain Fuel chief executive Darren Foote] and the Mountain Fuel supplements are insufficient for him to satisfy us he was not at fault or negligent."

Foote told the investigation he had told both athletes that other competitors had used the products, although the batch in question had not been tested for prohibited substances. He had been "shocked" at the positive results.

He subsequently accepted the supplements were the source of the banned substances and told the inquiry: "The only logical explanation is that something must have gone wrong during the blending, manufacturing or packaging process which led to the contamination."

Foote said the manufacturers, Cambridge Commodities Limited had not replied to his correspondence.

Speaking to BBC Wales before the report was published, Foote had said: "I'm not going to give stuff to them that has anabolic steroids in it... I'm just chuffed the guys are back in running."

Under the revised 2015 World Anti-Doping Code, national anti-doping bodies now have more flexibility in imposing sanctions for violations.

Serious cases of intentional doping can now result in a four-year ban, but the punishment for less serious offences can be reduced.

Nicola Newman, director of communications and education at UK Anti Doping, said that every athlete was "utterly responsible for what they consume".

She added: "We are pushing the risk particularly hard now because of the new code and if these athletes hadn't have been able to prove it was a contaminated batch they could possibly have got a four-year ban."

Williams had tested positive in both his A and B samples at the Glasgow Grand Prix on 11 July 2014, while 800m runner Warburton - the European Indoor runner-up in 2005 - was tested out of competition on 17 June.

Both athletes had to withdraw from the 2014 Commonwealth Games, where Williams had been set to be co-captain of Wales' athletics team.

The pair have both said they are looking forward to returning to competition and Williams has targeted qualifying for the 2015 World Championships in Beijing.