The World Health Organisation (WHO), on Tuesday said travellers should practice safe sex for no less than eight weeks after returning from areas with Zika infections, doubling the time period that was recommended in its previous guideline.

According to WHO spokesman in Geneva, new studies had shown that the virus is present in body fluids for longer than previously known.

The Zika outbreak in Latin American countries including Brazil, has raised concerns among scientists and athletes about the infection risk during the summer Olympics in Rio de Janeiro in August.

Zika is mostly spread through mosquitoes, but WHO noted in a new guidance document that mounting evidence has shown that sexual transmission of the Zika virus is possible and more common than previously assumed.

While most Zika patients recover quickly, the virus could cause brain malformations in unborn children, as well as other neurological disorders.

An international group of 151 scientists demanded in an open letter last week that the games in Rio be postponed or moved to avoid intensifying the spread of the Zika virus.

WHO disagreed and argued that the best way to stem the spread was to take precautionary measures, especially personal protection against mosquitoes and practising safe sex.