Full coverage: 2016 Rio Olympics

150 experts have called for the Olympic Games in Rio de Janeiro to be moved or delayed due to the Zika virus. Experts including international doctors, scientists and researchers from leading world institutions signed an open letter on Friday, which argued that pressing on with the Games in the Brazilian capital would be "irresponsible" and "unethical.

The World Health Organization had earlier said the Olympics and Paralympics "will take place during Brazil's wintertime when there are fewer active mosquitoes and the risk of being bitten is lower." But the group of experts worried that officials are not adequately protecting the public against the danger posed by Zika.

The letter said the mosquito-borne virus harms health in ways that science has not observed before. And large numbers of tourists to Brazil might acquire the virus, take it home where it could become endemic. It also questioned the neutrality of the WHO since the organization entered into an official partnership with the International Olympic Committee, in a Memorandum of Understanding that remains secret.