Federer calls for 'zero tolerance' amid Sharapova's doping ban

17-time Grand Slam champion Roger Federer has backed the two-year ban meted out to beleaguered Maria Sharapova while reiterating that he has a 'zero tolerance' stance against doping.

On Wednesday, the 29-year-old Russian was punished by a three-member Tennis Anti-Doping Program tribunal appointed by the International Tennis Federation for testing positive for the banned substance meldonium at January's Australian Open.

Meldonium was placed on the banned list by the World Anti-Doping Agency this year but the 2012 Olympic silver medallist said that she had been taking the drug since 2006 legally for years for health reasons and that she hadn't realised that the substance was no longer permitted.

Reflecting on the issue, Federer opined there was not much difference if someone consumes a banned substance purposefully or not, pointing out that an athlete should be completely aware of what goes inside his or her own body, Sport24 reported.

The Swiss maestro, who reached quarterfinals of the Stuttgart Open, further asserted that authorities should store blood samples of athletes for 10-20 years in order to scare away the potential cheaters.

However, Sharapova received an unexpected boost when sponsors such as Nike and Head decided to maintain their partnership with the Russian citing the ITF's assertion that she had not doped intentionally.

Meanwhile, the five-time major champion has described the punishment 'unfairly harsh' and vowed to take her appeal to the Court of Arbitration for Sport.