BERLIN — The World Health Organization said Saturday that there was no public health justification for postponing or canceling the Summer Olympics in Rio de Janeiro because of the Zika outbreak in Brazil.

On Friday, 150 health experts issued an open letter to the health agency calling for the Olympic Games to be delayed or moved in the name of public health. The letter cited recent scientific evidence that the Zika virus causes severe birth defects, most notably babies born with abnormally small heads. In adults, it can cause neurological problems, including a rare syndrome that can be fatal or result in temporary paralysis.

The experts also noted that despite increased efforts to wipe out the mosquitoes that spread Zika, the number of infections in Rio de Janeiro had gone up rather than down.

The experts came from more than two dozen countries in fields like public health, bioethics and pediatrics, and included a former White House science adviser, Dr. Philip Rubin.