Maria Sharapova's racket sponsor has come out in support of the Russian tennis player.

The 28-year-old announced on Monday that she had tested positive for a banned substance at the Australian Open in January.

Sharapova stressed that she had been taking a drug called meldonium on medical grounds for 10 years and that she did not realise it had been added to the World Anti-Doping Agency's list of prohibited substances at the turn of the year.

Major sponsors Nike, Porsche and TAG Heuer have since suspended their relationship with the five-time Grand Slam winner, which could reportedly lose her around £100m.

However, Head have announced that they plan to extend their contract with Sharapova.

The statement in full read: "Head is proud to stand behind Maria, now and into the future and we intend to extend her contract.

"For more than a decade, Maria Sharapova has been a role model and woman of integrity who has inspired millions of fans around the world to play and watch tennis.

"The honesty and courage she displayed in announcing and acknowledging her mistake was admirable. We look forward to working with her and to announcing new sponsorships in the weeks and months ahead.

"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."

Sharapova has been provisionally banned by the International Tennis Federation, who are expected to hand out a more definitive punishment in the near future.