The use of meldonium, the drug taken by Maria Sharapova, was common in tennis before it was banned, according to Dick Pound, chair of the World Anti-Doping Agency's investigation into Russian athletics.
Five-times grand slam champion Sharapova tested positive for the drug at this year's Australian Open and faces a ban of up to four years, pending an investigation by the International Tennis Federation (ITF).
Pound said on Wednesday Sharapova only had herself to blame for not realising meldonium, which some researchers have linked to increased athletic performance and endurance, had been outlawed since January 1.
He also suggested tennis authorities had been aware that many players were using the drug, a claim rejected by the ITF.
"Clearly within the tennis circles they were aware that a lot of players were using it, so there must be something in it," Canadian Pound told reporters at a conference on doping.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The ITF, which will provisionally ban former world No.1 Sharapova from this weekend, issued a statement in response to Pound's comments.
"The monitoring of substances is undertaken by WADA, and so tennis was not aware of the prevalence of meldonium use in 2015 (or before), prior to its addition to the Prohibited List.
"The ITF did not refer meldonium to the WADA list committee," it said.
Sharapova stunned the sporting world on Monday when she said she tested positive for meldonium, a drug available in eastern Europe to treat some heart conditions.
The world's highest-earning sportswoman who raked in $US29.7 million ($A39.83 million) last year, according to Forbes magazine, said she had taken the drug, for the past decade to treat health problems.
Pound had no sympathy for the 28-year-old though, saying she had been careless in the extreme.
"No, there is no excuse," Canadian Pound told Reuters.
"This is a woman who won her first Wimbledon title 12 years ago, she is in a sport which is known to have drug problems, she knows she is going to be tested.
"If you are running a $US30 million a year sole proprietorship, I'm sorry you damn well make sure that you don't do anything that makes you ineligible."
Pound said as far as he was aware Sharapova had not applied for a therapeutic use exemption (TUE) for meldonium, a product not available in the US where she lives but common in Russia.
He also said her positive test should serve as a warning to all tennis players.
"I think this would wake me up," Pound said.
"If you have an IQ higher than room temperature you should stop."
