The UK, Australia and Taiwan have posted travel advisories for Singapore after the city state confirmed an increase in the number of Zika cases to 56.
Health officials detected 15 more cases of locally-transmitted Zika on Monday centred on the Aljunied district mostly affecting foreign workers at a construction site.
It has got neighbour Malaysia worried which has announced thermal screening at checkpoints for travellers who enter the country from Singapore by bus.
Up to 200,000 people cross the Johor Strait between Singapore and Malaysia every day.
"The risk is imminent. The main thing is to reduce the risk of the virus spreading to others," said Subramaniam Sathasivam, Malaysia’s health minister.
While sporadic cases have been reported in other Southeast Asian nations, the Singapore outbreak is the biggest so far outside of the Americas region.
"Given that the Zika virus is spread by the Aedes mosquito vector, we cannot rule out further community transmission in Singapore, since some of those tested positive also live or work in other parts of Singapore," the Ministry of Health and National Environment Agency said in a joint statement.
