This summer's Rio de Janeiro Olympics should be moved or postponed because of the ongoing Zika virus, according to more than 150 global health experts.

In an open letter to the World Health Organisation (WHO) and the International Olympic Committee, the experts, including a former White House adviser, called into question the two organisations' close relationship and asked for the Games to be moved to another location or postponed "in the name of public health".

The letter cites that the Zika virus has more serious medical consequences than previously known and that the emergency contains "many uncertainties".

One co-author said that if this year's Games went ahead it risked becoming "the Olympics of brain damage".

WHO declared the Zika epidemic to be a global emergency in February and in its latest assessment this week, said it "does not see an overall decline in the outbreak".

Co-author of the letter, professor Amir Attaran, said that allowing the Olympics to go ahead would lead to the birth of more brain-damaged children.

The majority of those infected with Zika will have no symptoms, but for others it can cause a mild illness with symptoms including a rash, fever and headache.

Serious complications that arise from infection are not common, but experts have said the virus can cause microcephaly, where babies are born with abnormally small heads due to the fact their brains have not developed properly.

Some 500,000 foreign tourists are expected to attend the Games, which would lead to the virus being spread across the globe to areas it may not have reached if it was not for the Olympics, the letter warned.

WHO director-general Dr. Margaret Chan said earlier this month that the UN health agency is increasingly worried about Zika but stopped short of recommending the Olympics be moved or postponed.