Russia's suspended athletics federation said on Thursday it had missed a 1 July deadline to pay $5 million of a fine to World Athletics, jeopardising the chances of its track and field athletes being able to compete internationally as neutrals.
World Athletics, the sport's global governing body, in March handed the federation a $10million fine for breaching anti-doping rules.
World Athletics at the time reinstated the process by which Russian athletes could apply to compete internationally as neutrals after demonstrating that they train in a doping-free environment.
It said, however, that this process would again be suspended if half of the fine was not paid by 1 July.
The Russian federation told TASS agency on Thursday that the fine had not been paid as of 2 July, a day after the federation's president said it did not have sufficient funds to do so.
The federation was suspended in 2015 after a report commissioned by the World Anti-Doping Agency (WADA) found evidence of mass doping among track and field athletes in the country.
Russia is also in the process of appealing a four-year ban on its athletes competing at major international sporting events under their flag as punishment for the alteration of laboratory data.
Its case will be heard by the Lausanne-based Court of Arbitration for Sport (CAS) in November.