Two Ukrainian athletes, including an Olympic bronze medal winner, have received provisional suspensions after being charged with doping offenses, international sports officials say.
The International Association of Athletics Federations (IAAF) said sprinters Olesya Povh and Olha Zemlyak face charges of "the use of a prohibited substance" and have been suspended pending the outcome of any appeals in the case.
The suspensions come ahead of the World Athletics Championships, which begin August 4, meaning the two women will not be able to compete.
The Ukrainian Athletics Federation said Povh and Zemlyak had written to the IAAF but that "their explanations...were found to be insufficient to explain the abnormal test results."
The federation said Zemlyak's coach, Serhiy Basenko, was also removed from Ukraine's world championship delegation.
Povh won an Olympic bronze medal in the women's 4x100-meter relay in 2012 in London and had been due to race the 100 and 4x100 at the world championships, also in London.
Previously, Ukrainian javelin thrower Oleksandr Pyatnytsya and Denys Yurchenko were stripped of Olympic medals as part of doping investigations.
Russia will not have an official delegation at the event because of an ongoing suspension related to a 2015 probe that found evidence of state-sponsored doping and systematic violations of anti-doping regulations.
Some Russian athletes approved by international officials will be allowed to compete as "neutrals."