The Ukraine’s former European indoor 800m champion Nataliya Lupu will miss this week’s world indoor championships after she tested positive for meldonium.

Meldonium is the recently banned substance for which tennis champion Maria Sharapova tested positive during the Australian Open.

The Ukrainian track and field federation confirmed Lupu withdrew from the championships, which begin in Portland tomorrow, after the World Anti-Doping Agency raised concerns about the use of the drug.

Besides Lupu, at least 19 athletes from four countries have been provisionally suspended after testing positive for meldonium, including four Olympic medallists.

WADA said in September that meldonium, a popular heart medication in former Soviet nations, would be banned from January 1, citing evidence it enhanced performance and was being widely used by athletes who didn’t need it for medical reasons.

In a statement on her federation’s website, Lupu said she’d used meldonium for 15 years for medical reasons with doctors’ prescriptions because of “certain changes in her cardiogram”, but added she stopped taking the drug in November, two months before it was officially banned.

Lupu served a nine-month doping ban after testing positive for the banned stimulant methylhexaneamine at the 2014 world indoors in Sopot, Poland.

Meanwhile, the International Olympic Committee [IOC] said it will re-test hundreds of athletes’ samples collected at the 2008 Beijing and 2012 London Olympics in order to root out any cheats ahead of this year’s Rio Games.

Doping has overshadowed the run-up to the Olympics with scandals involving the IAAF, the governing body of athletics, track and field competitors plus several countries including Russia and Kenya who could still be excluded from the Games.

“The aim of the [re-testing] programme is to prevent athletes who cheated in London or Beijing, and got away with it because we didn’t have as advanced methods of analysis as we do now, from competing in Rio de Janeiro,” said IOC medical director Richard Budgett.

“The results will come in a number of weeks or months.”

Athletics, the showpiece sport of the Olympics, was rocked last year when Russia was suspended from the sport after a World Anti-Doping Agency [WADA] investigation uncovered a state-sponsored doping programme.

Kenya could also be banned if it doesn’t deliver on promises to WADA.