SINGAPORE - An outbreak of the Zika virus in Brazil has cast a shadow over the Olympics, which the country will host from Aug 5-21.

The mosquito-borne virus has mild symptoms, but is believed to be linked to a surge in cases of microcephaly, a condition in which a baby is born with an abnormally small head and brain.

The Singapore National Olympic Council (SNOC), which is responsible for Singaporean athletes at the quadrennial Games, said on Monday that it is monitoring the situation while steps have been taken to alert athletes of the threat.

In a press statement, Low Teo Ping, Team Singapore's chef de mission for the Rio Games, said: "The SNOC has received an advisory from the International Olympic Committee (IOC) regarding the Zika virus. We are monitoring the situation and developments closely with the IOC and the relevant local authorities and will remain guided by them.

"We have contacted the National Sports Associations preparing for the Olympic Games to advise the athletes and officials to take extra precautions, such as to minimise the risks and contact with mosquitoes when visiting areas susceptible to the virus and to take extra measures in preventing insect bites.

"The SNOC will continue to monitor the situation with vigilance and provide advice and assistance in the best interests of our athletes and officials' health and safety."

The disease is not as deadly as Ebola, but experts have warned of its danger due to the fact that there is currently no vaccine for the virus, and that an estimated 80 per cent of those infected do not display symptoms.

The Zika virus has spread to over 20 countries. Some 10,000 athletes are expected to compete at the Games, while hundreds of thousands of tourists are expected.

It has been linked to brain defects found in some 4,000 babies in the South American country. The World Health Organisation committee is meeting on Monday to decide on the appropriate international response.