European football's governing body have released a report which pins the blame on WADA for Sakho, who is now on loan at English Premier League club Crystal Palace, testing positive for a fat burner following a UEFA Europa League clash with arch-rivals Manchester United at Old Trafford on March 17.

The 27-year-old Frenchman was given a 30-day ban as a result, which caused him to miss Liverpool's Europa League final defeat to Sevilla in May and the European Championships in his native country in June and July.

In the report, UEFA, who dismissed the case against Sakho in July, claim the presence of higenamine in his sample should never have prompted a positive result.

The organisation also believe experts have cast doubt on whether the substance, in a group known as B2–agonists, is even on WADA's Prohibited List.

According to the Liverpool Echo, the club are considering legal action over the confusion and mishandling of Sakho's case.

"Higenamine is not expressly mentioned by name on WADA's prohibited list," the report says.

"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.

"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.”

In response to the accusations made by UEFA, WADA spokesperson Ben Nichols defended the actions of the organisation and insisted they had followed the correct procedure.

"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 Mr 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.

"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."

The full UEFA report can be read here.