The use of meldonium--the substance taken by tennis star Maria Sharapova--is widespread among elite athletes, reveals research published online in the British Journal of Sports Medicine.

The findings, which draw on information volunteered by athletes and individual medical teams, and lab data on anti-doping tests from the Baku 2015 European Games, indicate that up to 490 athletes may have been taking meldonium during the competition.

The research, which was carried out on behalf of the European Olympic Committees, contributed to the World Anti-Doping Agency (WADA) taking the decision to ban the use of meldonium in competitive sport as of January 1 this year.

Earlier this week, Ms Sharapova admitted that she had tested positive for meldonium after the introduction of the WADA ban.

The research highlights that at the time of the Baku 2015 European Games:

• 13 medallists or competition winners were taking meldonium