Maria Sharapova has "no excuse" for not realising that the medication she was taking had a banned ingredient in it, Dick Pound has said.
Speaking to ITV News, the former head of the World Anti Doping Agency said; "There's no excuse for somebody with her experience for testing positive for something she knew about and had been warned about.
She was either recklessly indifferent to what messages she was getting from Wada and the ATP or she did it deliberately and thought 'maybe I'll get away with it'".
Davis Cup-winning captain Leon Smith has extended his contract and will lead the Great Britain team for at least another three years.
The Scot succeeded John Lloyd in 2010 after Britain had suffered the ignominy of defeat by Lithuania and were on the verge of relegation to the competition's bottom tier.
Five years later Smith achieved what had appeared impossible and guided his country to a first Davis Cup title in 79 years with victory over Belgium.
After signing a deal until the end of 2018, which will also see him remain as the Lawn Tennis Association's head of men's tennis, Smith said: "It is a huge honour and privilege to continue captaining our Davis Cup team.
"We have achieved so much over the last six years and becoming world champions last year will be the highlight of my career."
The Russian government has said that Maria Sharapova's failed drugs test should not be "projected onto" the whole of Russian sport.
Kremlin spokesman Dmitry Peskov also told journalists that Russia was against attempts to politicise sporting matters.
Current and former tennis stars have been reacting on Twitter to Maria Sharapova's shocking announcement that she had failed a drugs test.Read the full story ›
Meldonium, the newly banned substance former world tennis number one Maria Sharapova has admitted to taking for 10 years, is reportedly only meant to be used for 'four to six weeks' at a time.
According to a statement emailed to the Associated Press the manufacturers of the drug said it is usually only administered for a short time but prescriptions can be repeated two or three times a year under medical advisement.
It is unclear whether Sharapova took the drug consistently for long periods over the last decade or whether the use of the substance was intermittent.
Depending on the patient's health condition, treatment course of meldonium preparations may vary from four to six weeks.
Treatment course can be repeated twice or thrice a year. Only physicians can follow and evaluate patient's health condition and state whether the patient should use meldonium for a longer period of time.
Evian has announced that is 'closely' following developments in the investigation into tennis star Maria Sharapova after she announced yesterday that she had failed a drugs test.
It comes as Sharapova lost her sponsorship deals with Nike, Tag Heuer and Porsche following the revelations.
The parent company of the water brand, Danone, said it was "surprised" after the star admitted taking what is now a banned medication but did not comment directly on the status of her current sponsorship deal.
Evian has been a partner of Maria Sharapova for many years, and until now, we have maintained a trustworthy professional relationship.
Evian attaches great importance to health, to integrity, and transparency, and we will follow closely the development of the investigation.
Caroline Wozniacki has said that athletes should make sure they "double, triple and quadruple check" their medications following revelations tennis star Maria Sharapova has failed a drugs test.
Speaking at a press conference in New York the Danish tennis star said athletes should be careful to check their medications for banned substances "because sometimes even things like cough drops and nasal sprays can be on the list".
Any time we take any medication I think we double and triple and quadruple check because sometimes even things like cough drops and nasal sprays can be on the list.
So I think as athletes we always make sure to really make sure there is nothing in it that could put us in a bad situation.
Serena Williams said she was "surprised and shocked" like everyone else to hear that fellow tennis player Maria Sharapova had failed a drugs test but praised her honesty in coming forward.
The women's world No. 1 tennis player said: "I think like everyone else said most people were surprised and shocked by Maria.
"But at the same time I think most people were happy that she was upfront and very honest and showed a lot of courage to admit to what she had done and what she had neglected to look at."
A member of the Russia men's volleyball team has reportedly tested positive for the same banned substance as Maria Sharapova.
The R-Sport news agency said meldonium had been detected in a sample given by 25-year-old Alexander Markin.
Russia's sports minister had earlier predicted more cases would emerge involving the nation's athletes in the wake of Sharapova's failed test.
Porsche has become the latest sponsor to change its relationship with Maria Sharapova after she announced she had failed a drugs test at the Australian Open.
The sports car manufacturer said it had postponed all planned activities with the five-time Grand Slam champion until further details are released.
The International Tennis Federation (ITF) is due to issue a final decision on a recommended punishment for Sharapova, which will be reviewed by the World Anti-Doping Agency.