World No.2 and five-times grand slam champion Iga Swiatek has accepted a one-month suspension after testing positive for banned substance trimetazidine in the latest doping controversy involving a star tennis player.
Swiatek tested positive in an out-of-competition sample in August but the International Tennis Integrity Agency accepted it was caused by contamination of her medication melatonin, which was manufactured and sold in Poland.
Swiatek had been taking it for jet lag and sleep issues and as there was no significant fault or negligence, the ITIA offered the reigning French Open champion a one-month suspension, which the 23-year-old accepted.
"The player was provisionally suspended from September 12 until October 4, missing three tournaments, which counts towards the sanction, leaving eight days remaining," the ITIA said in a statement on Thursday.
"In addition, the player also forfeits prize money from the Cincinnati Open, the tournament directly following the test."
Swiatek, who had pulled out of tournaments in Asia in September citing personal matters and fatigue, described the ordeal of testing positive as the "worst experience of my life".
She was world No.1 when she failed the test and having skipped the Asian swing, Aryna Sabalenka leapfrogged her in the world rankings to eventually end the year as number one.
"In the last 2.5 months I was subject to strict ITIA proceedings, which confirmed my innocence," Swiatek said on Instagram.
"The only positive doping test in my career, showing unbelievably low level of a banned substance I've never heard about before, put everything I've worked so hard for my entire life into question.
"Both me and my team had to deal with tremendous stress and anxiety. Now everything has been carefully explained, and with a clean slate I can go back to what I love most."
Swiatek is not the first world No.1 to fail a doping test this year after Italy's Jannik Sinner, the men's top-ranked player, also tested positive for anabolic agent clostebol.
However, Sinner was cleared of wrongdoing by an independent tribunal ahead of the US Open, which he went on to win.
Swiatek played in Cincinnati, where she was the top seed and reached the semi-finals. The WTA said she won nearly $US159,000 ($A245,000) in prize money at the tournament won by Sabalenka.
Swiatek then took part in the US Open where she was knocked out in the quarter-finals before the WTA Finals in Riyadh, in which she failed to advance from the group stage.
She also represented Poland at the Billie Jean King Cup where they lost in the semi-finals to eventual champions Italy.
The women's tour (WTA) said they acknowledged the ITIA's decision and that they "fully support" Swiatek.
"Iga has consistently demonstrated a strong commitment to fair play and upholding the principles of clean sport, and this unfortunate incident highlights the challenges athletes face in navigating the use of medications and supplements," the WTA said.
Russian figure skater Kamila Valieva also tested positive for TMZ, with the result revealed during the 2022 Winter Olympics. She was disqualified from the team competition at the Beijing Games and was handed a four-year doping ban.
