Russian President Vladimir Putin waded into the debate over meldonium on Thursday, saying the banned substance should not be considered a performance-enhancing drug.

There have been at least 172 failed drug tests for meldonium worldwide since the Latvian-made heart-drug was banned in 2016. Russian athletes - including tennis star Maria Sharapova - make up the largest contingent of those who have tested positive.

''This substance was never considered as doping,'' Putin said during a marathon phone-in program on Russian television. ''It doesn't influence the result. That's totally certain. It just keeps the heart muscles in good condition under high load.''

Among those watching in the studio was Ekaterina Bobrova, an Olympic gold medal-winning ice dancer who is suspended after testing positive for meldonium.

The company which makes meldonium has marketed it as improving energy levels in heart patients, while its inventor has previously said it increased the endurance of Soviet troops. However, the company also says meldonium should not be considered a performance-enhancer.

Meldonium was routinely used as a supplement by athletes in Eastern Europe before it was banned.

While Putin said he did not think authorities were targeting Russia in the decision to ban meldonium, he criticized the World Anti-Doping Agency for not carrying out research earlier on how long the drug takes to leave the body.

''There was no proper data,'' he said.

Some athletes say they stopped taking meldonium before it was banned but have still tested positive, and WADA said Wednesday that athletes in that position could avoid sanctions if that argument is backed up by data showing a low concentration of the substance in their sample.

Putin was noncommittal when asked by Russian track head coach Yuri Borzakovsky about the team's chances of being allowed to compete at the Olympics in August. Russia was suspended from global track and field in November after a WADA report detailed widespread, state-sponsored drug use.

''They're obviously in a hard situation but you have to be ready for anything, it seems to me, if you ask my opinion,'' Putin said. ''Of course we will fight for decisions to be fair. The Russian Sports Ministry, our sports organizations are working with good lawyers at a world level on this issue and are studying all aspects of the topic.''

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