Two-time Grand Slam champion Simona Halep has been banned for four years following breaches of the Tennis Anti-Doping Programme.
An independent tribunal determined the 31-year-old Romanian had committed “intentional” anti-doping violations.
Halep tested positive for the use of roxadustat at last year’s US Open.
She was also found guilty of using an unspecified prohibited substance or method in 2022 after irregularities were found in her biological passport.
The tribunal accepted Halep’s argument she had taken a contaminated supplement, but decided that would not have resulted in the concentration of roxadustat found in her urine sample.
The panel also stated they had no reason to doubt the unanimous “strong opinion” reached by three independent experts that “likely doping” was the explanation for the irregularities in her biological passport.
Halep has been provisionally suspended since October 2022, which means she will be able to play again on 7 October 2026, by which time she will be 35.
The findings of the tribunal, however, can be appealed against and Halep said in a statement she would challenge the verdict.
Halep said: “The last year has been the hardest match of my life, and unfortunately my fight continues. I have devoted my life to the beautiful game of tennis.
“I take the rules that govern our sport very seriously and take pride in the fact I have never knowingly or intentionally used any prohibited substance. I refused to accept their decision of a four-year ban.”
Halep, who won the French Open in 2018 and Wimbledon the following year, is the highest-profile tennis player to fail a drugs test since Maria Sharapova in 2016.
She has won 24 WTA tour singles titles and earned £32.2m ($40.2m) in prize money and was ranked number one in the world in 2017 and 2018.