Uefa has heavily criticised the World Anti-Doping Agency for wrongly flagging up a positive drug test by the Liverpool defender Mamadou Sakho after he took a fat-burner without the club’s knowledge last year.

Sakho, who is now on loan at Crystal Palace, was suspended at the end of April 2016 after testing positive for higenamine following the second leg of Liverpool’s Europa League last-16 tie against Manchester United the previous month. However, in early June Uefa’s disciplinary body absolved Sakho of taking a performance-enhancing drug and on Thursday European football’s governing body went further still, releasing a damning report pointing out that higenamine is not specifically listed on Wada’s prohibited list.

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The report also suggested there are significant doubts among experts about whether higenamine is among a group known as B2–agonists, all of which are banned by Wada – and pointed out that Wada’s laboratories do not routinely test for the substance and that if Sakho’s sample had been handled by the Lausanne laboratory and not Cologne’s then it would not have been tested for higenamine.

The Uefa report added: “Higenamine is not expressly mentioned by name on Wada’s prohibited list. The fact that the Cologne laboratory tested for higenamine but had to check with Wada before making a determination indicates a problem, as does the fact that the Lausanne laboratory does not test for higenamine at all.

“In this regard, Dr Saugy [giving evidence] explained that he has not received any formal instruction from Wada to test for higenamine and explained that the Lausanne laboratory would not start testing for higenamine until such communication is received.”

It continued: “The onus is clearly on Wada to communicate to its laboratories what is and what is not on the prohibited list. There are clearly gaps in communication with regard to higenamine, something which also tends to support the suggestion that Wada’s own internal procedure and analysis in respect of this substance is incomplete.”

Sakho was suspended by Liverpool when Jürgen Klopp, their manager, and the club’s owner, Fenway Sports Group, agreed it would be prudent to omit him from games while the investigation commenced, and he was then provisionally suspended by Uefa. Among the games he missed was the Europa League final, which Liverpool lost 3-1 to Sevilla after leading at half-time, and he was also omitted from France’s squad for Euro 2016.

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At the time Michele Verroken, director of Sporting Integrity and formerly in charge of anti-doping in the UK, said she advised athletes against using any substances described as fat-burners. “What is causing that fat to burn is that these supplements contain a form of stimulant,” she said. “They are not regulated products. It’s just too big a risk. I warn against any weight-loss products. It’s probably going to be a prohibitive supplement.”

Sakho fell out with Klopp having been sent home from a pre-season tour for reporting late for a series of team meetings during the trip to the United States, after which he was accused of displaying “a lack of respect.” But having missed the early part of the season with an achilles injury he has prospered after joining Palace in January.

However Wada spokesman Ben Nichols insisted that many of Uefa’s criticisms were misplaced. “Higenamine has been considered prohibited ever since the 2004 Prohibited List, however it was expressly named [for the first time] on the 2017 List as an example of a selective and non-selective beta-2-agonist,” he said.

“With regards to the case of Mamadou Sakho, Wada, with the support of its List Expert Group, thoroughly reviewed the full case file along with recently published articles on higenamine. Wada supported the List Expert Group’s unanimous view that higenamine is a beta2-agonist and does indeed fall within the S3 class of the Prohibited List. It was decided, however, after careful review of the specific circumstances of the case, that Wada not lodge an appeal.”

He added: “Whilst higenamine has been considered prohibited since 2004, its prevalence within dietary supplements has surfaced more recently. Therefore, in early August 2016, Wada requested its network of accredited laboratories to implement systematic testing for higenamine; although, it is clear that some laboratories already conducted routine testing for higenamine before this date.”