Players at grand slam tournaments and events sanctioned by the ITF, ATP and WTA are tested for substances prohibited by the World Anti-Doping Agency.
Yastremska drew a provisional suspension by the ITF on January 7.
In a statement on her Twitter feed then, Yastremska said she was “astonished and under shock”.
“I firmly state that I have never used any performance enhancing drugs or any prohibited substances,” she said.
She said she passed a drug test at her most recent tournament, in Austria on November 9.
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The ITF has said Yastremska provided an out-of-competition urine sample on November 24 which was sent to a WADA laboratory in Canada.
They said Yastremska was charged with an “anti-doping rule violation” on December 22, with the provisional suspension taking effect on January 7.
Yastremska has won three WTA singles titles. She reached a career-high ranking of No.21 a year ago. Her best showing at a major was reaching the fourth round at Wimbledon in her main-draw debut there in 2019.
With AP