The World Anti-Doping Agency (Wada) has confirmed 99 positive tests for meldonium since the drug was added to its banned list in January.

Wada would not go into specific details about the sports or countries involved but its finding underline the extent of the issue in elite sport.

Wada spokesman Ben Nichols said on Twitter: "Number of Meldonium positive (Adverse analytical findings) samples today at 99 since substance was banned on 1 January 2016 Wada_ama #Wada"

Maria Sharapova revealed this week that she tested positive at the Australian Open in January, claiming she missed an e-mail in September stating it had been added to the banned list.

Sharapova insists she had been taking meldonium on medical grounds for almost 10 years to cure an array of ailments including flu symptoms, diabetes and a heart complaint.

And her protestations were backed up by the chairman and chief executive of her racket sponsor, Head, who issued an statement backing the athlete and criticising Wada for black-listing the substance.

Johan Eliasch said Wada should have continued to allow some usage of the drug on medical grounds as he reiterated his company's strong support for the Russian superstar, who is facing the prospect of a lengthy ban

Despite a number of her sponsors, including Nike and Porsche, distancing themselves from Sharapova, Head issued a bullish statement on Thursday offering the player its full support and a contract extension.

And Eliasch went a step further on Friday with a second, strongly-worded statement in which he denied any “evidence or intent” by the player to gain a competitive advantage by using meldonium.

Eliasch said: “Although it is beyond doubt that she tested positive for a Wada-banned substance, the circumstantial evidence is equally beyond doubt that the continued use of meldonium after January 1, 2016 in the doses she had been recommended, which were significantly short of performance-enhancing levels, was a manifest error by Maria.

“In the absence of any evidence of any intent by Maria of enhancing her performance or trying to gain an unfair advantage through the use of [meldonium], we further conclude that this falls into the category of ‘honest’ mistakes.

“Furthermore, we question Wada’s decision to add meldonium to its banned substances list in the manner it did; we believe the correct action by Wada would have been to impose a dosage limitation only. In the circumstances we would encourage Wada to release scientific studies which validates their claim that meldonium should be a banned substance.

“The honesty and courage she displayed in announcing and acknowledging her mistake was admirable. Head is proud to stand behind Maria, now and into the future and we intend to extend her contract.

“Maria may have made a mistake, but she has earned the benefit of the doubt and we are extending it to her. We look forward to many more years of working with Maria.”

Wada responded by intimating it believed Eliasch’s response to be “inappropriate”, adding it would only review decisions after the respective governing bodies and national anti-doping agencies had issued their full rulings.

In a statement the organisation said: “Wada believes it is inappropriate for the agency [Wada], and indeed any other parties, to comment on the specifics of any of the meldonium cases until the International Federations or National Anti-Doping Agencies in charge with the result management of the cases have issued their decisions.

“At that time, and not before, Wada will review the cases in full, the reasons for the decision, and subsequently decide whether or not to lodge its independent right of appeal to the Court of Arbitration for Sport (CAS).

“The List is updated annually and with a full and thorough consultation period with experts and stakeholders. A substance or method may be added to the list of it meets two of the following three criteria: enhances performance; detrimental to the health of the athlete; contrary to the spirit of sport.”