World Anti-Doping Agency (WADA) Director General Olivier Niggli has stated that Russia's anti-doping reforms are not happening quick enough.
Following the publication of the McClaren report last year, in which it was claimed more than 1,000 Russian athletes took part in state-sponsored doping between 2011 and 2015, Russia was suspended from all international athletics competitions.
The Russian federation promised to improve the country's record on doping.
Speaking to BBC Sport, Niggli said "It is not happening at the speed I would like to see but its happening."
Russia announced they have implemented a number of changes which will soon see them return to international competition. It is expected the Russians will be allowed back to compete at international athletics events following the 2017 World Athletics Championships in London held this summer.
The comments made by the WADA chief are in contrast to those made by IAAF President Lord Sebastian Coe last month. Coe said "I think we should acknowledge that progress is being made".
Speaking to the BBC, Coe said there was a real chance Russia could be allowed back following the World Championships in London.