Kenya and Ethiopia have been listed by the IAAF (International Association of Athletics Federations) as two of the countries most likely to dope under new regulations.
They are joined by Belarus and Ukraine in what the governing body call Category A. These far-reaching decisions were taken by the IAAF Council in Buenos Aires, Argentina, on Saturday.
It means that athletes from these federations will have to undergo at least three out-of-competition doping tests in the 10 months before a world championship or Olympic Games.
Previously, the obligations under the IAAF Anti-Doping Code were focused primarily on individuals rather than national governing bodies.
The Athletics Integrity Unit (AIU) recommended the new regulations to the IAAF as a crucial step in helping clean up the sport.