MONTREAL (AFP) - The World Anti-Doping Agency (Wada) has recorded 123 cases involving meldonium since the endurance-boosting drug was banned on Jan 1, a spokesman said on Thursday.

Wada spokesman Ben Nichols confirmed the tally in a posting on Twitter.

"Currently 123 meldonium positives since substance was banned on 1st January 2016," Nichols wrote.

Meldonium was catapulted into the headlines earlier this month after it was revealed as the substance involved in Russian tennis star Maria Sharapova's failed drugs test at the Australian Open.

The identities of all of the athletes involved in the meldonium cases since the start of the year have not been disclosed.

Russian Olympic swimmer Yulia Efimova is among a crop of high-profile athletes to test positive for the substance.

Swedish middle-distance runner Abeba Aregawi and 2015 Tokyo Marathon winner Endeshaw Neggesse have also tested positive for the substance.

Meldonium is used to treat ischemia, a lack of blood flow to parts of the body.

The drug is manufactured in Latvia and prescribed to treat heart disease.