Two-time Grand Slam champion Simona Halep has been banned for four years following breaches of the Tennis Anti-Doping Programme (TADP).
The International Tennis Integrity Agency (ITIA) confirmed on Tuesday the ban of the Romanian for two separate anti-doping rule violations.
Halep tested positive for the use of banned roxadustat, a substance that increases the production of red blood cells to help athletes' endurance, at last year's US Open.
The 31-year-old was also found guilty of using an unspecified prohibited substance in 2022 after irregularities were found in her biological passport.
An ITIA statement reads: "The first (charge) related to an Adverse Analytical Finding (AAF) for the prohibited substance roxadustat at the U.S. Open in 2022, carried out through regular urine testing during competition.
"The tribunal accepted Halep's argument that they had taken a contaminated supplement, but determined the volume the player ingested could not have resulted in the concentration of roxadustat found in the positive sample.
"The second charge related to irregularities in Halep's Athlete Biological Passport (ABP)."
It is understood that the ABP charge was upheld because three independent experts were unanimous that "likely doping" was the explanation for the irregularities in her biological passport.
The case remains subject to appeal and Halep, who has been provisionally suspended since October 2022, has vowed to challenge the verdict.
"The last year has been the hardest match of my life, and unfortunately my fight continues," Halep said.
"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 turned professional in 2006, won her first major when she beat Sloane Stephens at the 2018 French Open and her second when she defeated Serena Williams to claim a maiden Wimbledon title in 2019.