China has warned its citizens to take "stringent" measures to reduce the risk of Zika infection when travelling to Singapore, where the number of cases has risen to 292, including 21 Chinese nationals in the city.
The General Administration of Quality Supervision, Inspection and Quarantine has also ordered mainland ports to increase health checks, quarantine controls and epidemic monitoring.
To avoid mosquito bites, the authorities urged tourists to wear light-coloured, long-sleeved shirts and trousers, and use repellent and netting while sleeping. If bitten, people should see a doctor quickly, it said in an alert on Wednesday.
Mainland China has yet to report any locally transmitted infections. Dozens of residents in Guangdong, Jiangxi, Zhejiang and Beijing who were confirmed to have the virus had contracted it while travelling abroad, the South China Morning Post reported.
Other South-east Asian countries, including Malaysia, the Philippines and Thailand, have also reported cases.
Dr Lu Hongzhou, a leading infectious diseases expert at the Shanghai Public Health Clinical Centre, told the Post the method of transmission - from mosquitoes to humans to mosquitoes - was straightforward and so the "globalisation" of the virus was inevitable.
China will also offer free Zika health screenings for travellers from Singapore and other affected countries, the quarantine bureau said. China previously announced that it would step up checks on people and goods from Singapore.
The authorites said on Wednesday that people showing Zika symptoms should report to quarantine officials when entering China.
Chinese international airports are generally equipped with thermal scanners that are capable of screening passengers for fever as they pass through Customs.
During past outbreaks, including of Sars and H1N1, passengers have been required to fill out health declaration forms.
Reuters reported there have been no obvious signs that Beijing is especially nervous about a Zika outbreak in China, aside from ordering the stepped-up checks on travellers.