British health officials have urged pregnant women to consider postponing non-essential travel to Florida after the southern US state confirmed the first cases of the Zika virus that were not linked to travel.
Florida, a popular holiday destination for Britons, reported four cases of local transmission on Friday.
Officials said that those infected had probably been bitten by a mosquito, and said they suspected the cases originated in an area north of downtown Miami.
"Pregnant women should consider postponing non-essential travel to affected areas until after the pregnancy," Public Health England, the government's public health agency, said on Saturday.
It said the risk in Florida from Zika was considered moderate based on the number and spread of cases.
The current outbreak of the Zika virus was first detected in Brazil last year and has since spread rapidly through the Americas. It can cause birth defects including serious brain abnormalities.