World number two Andy Murray has said Maria Sharapova should be banned due to her positive test for meldonium and questioned the Russian's claim she used the drug for medical purposes.
Murray harshly criticised his own racket manufacturer Head following its statement that it would continue to support Sharapova after she admitted that she had taken the banned substance.
"It's not up to me to decide the punishment, but if you're taking performance enhancing drugs and you fail a drugs test, you have to get suspended," Murray told reporters at the Indian Wells tournament in Palm Springs on Thursday.
Former tennis world No.1 Maria Sharapova said on Monday that she failed a drug test at the Australian Open due to taking meldonium for health issues.
"It is very important for you to understand that for 10 years this medicine was not on WADA's banned list and I had been legally taking the medicine. But on January the first, the rules have changed and meldonium became a prohibited substance," she stated.
The drug, produced in Latvia but unavailable for purchase in the United States where Sharapova is based, was only added to the World Anti-Doping Agency (WADA) list of banned substances in January, shortly before her positive test at the Australian Open.
That drug was manufactured for people suffering from heart problems, but can also increase blood flow and improve exercise capacity.
She said she was first given the drug by a family doctor after she frequently became sick, had irregular electrocardiogram results, a magnesium deficiency and a family history of diabetes.
She said she has been taking the drug for ten years.
"If you're taking a prescription drug and you're not using it for what that drug was meant for, then you don't need it, so you're just using it for the performance enhancing benefits that drug is giving you. And I don't think that that's right," he claimed.
"I read that 55 athletes have failed tests for that substance since January 1," Murray said.
Sharapova will be provisionally suspended from the International Tennis Federation from this weekend and may receive a four-year ban due to testing positive for the drug.
Sharapova, the highest-paid woman in sports, has lost support from some sponsors, with Swiss watchmaker TAG Heuer cutting ties this week, while Nike and Porsche have distanced themselves from her.
"I was getting sick a lot. I was getting the flu every couple of months. I had irregular EKG results," she said.
"I don't really know what else to say on that, but that's not something I believe," Murray said.
Murray said Head's announcement that it had extended its contract with the five-times grand slam champion was "a strange stance" given the events of the last few days.
"I think at this stage it's important really to get hold of the facts and let things play out, like more information coming out before making a decision to extend the contract like that, in my view. I personally wouldn't have responded like that."