World Athletics has banned transgender female athletes from competing in the female category at international events.
The governing body's president, Lord Coe, said no female transgender athlete who had gone through male puberty would be permitted to compete in female world ranking competitions from 31 March.
A working group will be set up to conduct further research into the transgender eligibility guidelines.
"We're not saying no forever," he said.
Lord Coe added the decision was "guided by the overarching principle which is to protect the female category".
More to follow.