Cases of the virus, which is spread by mosquitoes, have been rising in the country and the rest of the Americas ahead of Rio 2016.

Pregnant women have been advised not to travel to impacted areas due to a link between the virus and microcephaly - a condition which can lead to babies being born with small heads and under-developed brains.

Other symptoms include fevers, rashes, joint pain and conjunctivitis.

Uğur Erdener, the qualified doctor who chairs the International Olympic Committee's (IOC) Medical and Scientific Commission, has said that he believes Brazil is taking "significant" steps to combat the problem.

Today's announcement by the WHO, an agency associated with the United Nations, however, will only increase anxiety with thousands of athletes, officials and fans due in Rio de Janeiro.

It means that the Zika virus is considered to be in the same category as Ebola, which killed over 10,000 people in Africa between 2013 and this year.

“Members of the committee agreed that the situation meets the conditions for a public health emergency of international concern," said WHO director general Margaret Chan.

"I have accepted this advice."

Chan added that increased numbers of microcephaly cases represented an "extraordinary" event.

Funding will now be released to speed up the search for a cure, with no vaccine currently available.

Erdener said he was hopeful that as the Olymics take place in August, the mosquitoes responsible will not be as prevalent as it is a winter month in Brazil.

"In general, the Brazilian authorities are taking significant steps to deal with Zika, as they have recently announced that over 200,000 members of the armed forces and health workers will be engaged across the country, going from house to house to distribute leaflets and dispense advice about how to combat the mosquitos and the virus," he said.

There are 186 days to go before the Rio 2016 Opening Ceremony is due to take place on August 5.