Porsche suspend ties with Maria Sharapova after doping revelation

German luxury car-maker Porsche has suspended ties with Russian tennis star Maria Sharapova, the world's highest-earning female athlete in 2015 for the 11th straight year. Sharapova was Porsche's brand ambassador from 2013 and the suspension has been initiated after she failed a drug test conducted at the Australian Open earlier this year.

Porsche said Tuesday it postponed planned activities with Sharapova "until further details are released and we can analyse the situation," reports USA today.

The five-time Grand Slam champion said she had been taking the drug meldonium, prescribed by her doctor, for 10 years. She said Monday she was unaware it was added to the list of banned substances by the World Anti-Doping Agency (WADA) in January 2016. Sharapova claimed she was taking the drug because she has magnesium deficiency and a family history of diabetes.

As the brand ambassador of Porsche, Sharapova has been promoting different models including the Boxster Spyder. Sharapova has also appeared in commercials of the brand. She also owns a one-off Panamera GTS created specifically for her.

Swiss watch-maker Tag Heuer and American sportswear brand Nike also suspended ties with the tennis star Tuesday. Her earnings were about $30 million in 2015 from endorsements and winnings. Her association with Nike started when she was just 11 years old.