LONDON (Reuters) - Maria Sharapova will attend an International Tennis Federation anti-doping hearing in London on Wednesday, British media reported, with the Russian facing a possible ban of up to four years for failing a drugs test at the Australian Open.

The five-time grand slam champion stunned the world in March when she said she had returned a positive test for meldonium, a Latvian-made heart medication which was added to the World Anti-Doping Agency's (Wada) banned list from Jan 1.

Sharapova, the world's highest-paid sportswoman, claimed to have been taking meldonium on doctor's orders for 10 years and had failed to note that it had become a banned substance until hearing of her failed test at the first grand slam of the year.

She was provisionally suspended on March 12 pending the hearing.

Hundreds of athletes have tested positive for meldonium this year but Wada admitted last month that their bans might be overturned due to a lack of clear scientific information on how long the drug takes to be excreted from the body.

The drug's manufacturer said traces could remain in the body for several months depending on dosage, duration of treatment and sensitivity of testing methods.

The ITF's anti-doping programme calls for a four-year suspension for a failed test but it can be reduced in various circumstances, such as for first-time offences or if the player shows no significant fault or negligence.