Nikolai was found to have the forbidden substance Trimetazidine in his urine sample, which was taken in Kenya on February 5, 2015.

Nikolai admitted to taking the drug but claimed he was not aware that it was prohibited while he was not competing.

Nikolai notified the Estonian Athletics Association that he was ready to cooperate with them in the probe.

In another statement Erich Teigamagi said "Together with the IAAF, the World Anti-Doping Agency and Antidoping Estonia are working consistently to combat banned substances and methods.

The Estonian Athletics Association is working closely with IAAF and Antidoping Estonia.