The IAAF review board has appealed to the Court of Arbitration for Sport (CAS) against the decision by the Bulgarian Federation to clear two athletes of doping violations.
High jumper Venelina Veneva and Vanya Stambolova, who competed in the 400m and 400m hurdles, tested positive for testosterone or its precursors in January but the Bulgarian Federation lifted their provisional bans after a disciplinary hearing.
The federation said the analysis made by the World Anti-Doping Agency's (WADA) accredited laboratory in Lausanne was not correct and refused to suspend the two women.
The move by the governing body of athletics means Veneva and Stambolova will miss this month's World Championships in Japan.
Veneva, 33, won the silver medal at last year's European Championships where Stambolova, 23, took the 400 title.