A spokesperson for US Centres for Disease Control said evidence is mounting to suggest local transmission via mosquitoes is going on in South Florida.'

London - Concerns have been raised that the Zika outbreak in the popular holiday destination of Florida could be mosquito-borne, meaning the virus has established itself on the US mainland for the first time.

Florida has already seen more than 300 Zika cases linked to travel abroad.

Officials are warning tourists to discuss their travel plans with their GP, “particularly if you’re pregnant or planning to become pregnant”.

A spokesperson for US Centres for Disease Control said “evidence is mounting to suggest local transmission via mosquitoes is going on in South Florida.”

Public Health England said that if the cases are confirmed to have been spread by mosquitoes, it would advise pregnant women against “non-essential travel” to the state.

Paul Cosford, PHE medical director and director of health protection, said: “We know the Aedes aegypti mosquito, which is known to carry Zika virus, is present in Florida ... If the cases in Florida are confirmed then the risk would be considered moderate and pregnant women would be advised to consider postponing non-essential travel.

“Advice to all travellers remains to avoid mosquito bites.”