Sportswear giant Nike has suspended its multi-million dollar deal with tennis star Maria Sharapova after it was revealed she failed a drug test at this year's Australian Open.

The company released a short statement confirming the decision, which followed the announcement the 28-year-old tennis star and richest female sportsperson had positive for Meldonium after losing to Serena Williams on January 26.

"We are saddened and surprised by the news about Maria Sharapova," Nike's statement read.

"We have decided to suspend our relationship with Maria while the investigation continues.

"We will continue to monitor the situation."

In revealing the positive test today, Sharapova said she was first prescribed the drug in 2006.

It was only added to a banned list of substances in recent months.

"I had several health issues going on at the time," she told a press conference at Los Angeles hotel today.

"I was getting sick very often.

"It made me healthy so I continued to take it.”

Sharapova said she originally began taking Meldonium for a variety of worrying symptoms, including an irregular heart test and a family history of diabetes.

Meldonium is used to treat heart trouble, including angina and heart failure.

The International Tennis Federation (ITF) said Sharapova has been "provisionally suspended with effect from March 12 pending determination of the case" in a statement on its website.

Sharapova said she received an updated list of banned substances for the Australian Open on December 22 last year, which included Meldonium, but failed to look at it.

Produced in Latvia, Meldonium is one of the country’s biggest exports, and is not licenced to be sold in Australia.

Sharapova, who won Wimbledon in 2004 when she was just 17 years old, said she takes full responsibility for the failed test.

Sharapova won Wimbledon when she was just 17 years old and is ranked seventh in the world. (AAP)

"I have made huge mistake and I have let my fans down. I’ve let the sport down," she said.

"I know I face consequences and I didn't want to end my career this way. I hope I will be given the chance to play this game again."

She admitted she was not sure what the consequences of the test results would be.

"This is very new to me," she said.

"I just received the letter a few days ago, and I will be working with the ITF."

Asked if the doctor who prescribed the drug should have been aware it was now banned, Sharapova refused to shift the blame.

"I have to take full responsibility for it," she said. "It's very important to have a great team around you ... but at the end of day, everything you do is about you."

Sharapova at today's press conference. (AAP)

Former US star Jennifer Capriati took to Twitter to suggest Sharapova should be stripped of her grand slam titles.

Capriati, who won three majors, was scathing of Sharapova and sceptical of her explanation for taking a heart medication without a major heart condition.

"In my opinion if it's all true every title should be stripped. This is other people's lives as well," Capriati posted on Twitter.

"What's the point of someone taking a heart medicine that helps your heart recover faster unless you have a heart condition? Is that accurate?"

Capriati, whose own career spectacularly unraveled when was arrested for marijuana possession, added: "I'm extremely angry and disappointed. I had to lose my career and never opted to cheat no matter what. I had to throw in the towel and suffer."

Sharapova burst onto the international scene as she giggled and grunted her way to the Wimbledon crown in 2004.

She won the US Open in 2006, the Australian Open in 2008 and the French Open in 2012 and 2014.

Her ferocity on the court, business acumen and glamorous looks have all combined to make her a marketing juggernaut and the overseer of successful ventures such as her Sugarpova line of candy.

She has 35 WTA singles titles and more than $36 million in career earnings, and is currently ranked seventh in the world.