Ukrainian sprinters Olesya Povkh and Olha Zemlyak were provisionally suspended on the eve of the IAAF World Championships after being charged with doping offences.
The Athletics Integrity Unit (AIU) on Thursday revealed that Povkh and Zemlyak have been banned from competing in London due to failed drugs tests.
The AIU stated that Povkh, winner of Olympic and World Championship relay bronze medals, and Zemlyak had attempted to explain the adverse findings, but letters they submitted were "insufficient to explain the abnormal test results."
Povkh was due to represent her country in the 100 metres and 4x100m relay at the World Championships, while Zemlyak should have taken to the track for the 400m and 4x400m relay.
The Ukrainian Athletics Federation also revealed that Zemlyak's coach, Sergiy Basenka, will also be prevented from playing any part in the World Championships.
Povkh and Zemlyak will remain provisionally suspended until the outcome of their cases.