The Zika virus could spread to Europe this summer, although the likelihood of an outbreak is low to moderate, the World Health Organization has said.
Areas most at risk are those where Aedes mosquitoes may spread the virus, like the Black Sea coast of Russia and Georgia and the island of Madeira.
Countries with a moderate risk include France, Spain, Italy and Greece, while the risk in the UK is low.
The UN agency is not issuing any new travel advice at this time.
The WHO is calling on countries to eliminate mosquito breeding sites and to make sure that people - particularly pregnant women - have information on the potential harmful consequences of the disease.
The agency says most countries that could be affected are well prepared to pick up any new cases and deal with them quickly - but others must bolster their ability to diagnose the virus.
Brain defects
Zika has been linked to a rise in brain defects in babies and the virus has been seen in more than 50 countries during this outbreak.
And WHO experts say the risk of spread increases in late spring and summer as Aedes mosquitoes - thought to carry the virus - become more active.
The report suggests 18 countries are at moderate likelihood of seeing Zika cases while the UK is one of 36 countries which have a low, very low or no likelihood of transmission.
Dr Zsuzsanna Jakab, at the WHO, said: "We call particularly on countries at higher risk to strengthen their national capacities and prioritise the activities that will prevent a large Zika outbreak."
Meanwhile Prof Jimmy Whitworth, at the London School of Hygiene & Tropical Medicine, said the the risk of Zika spreading to Europe was real and called for holidaymakers to heed health advice.
He added: "The main mosquito vector for Zika, Aedes aegypti, is only found in Madeira and around the Black Sea, but another mosquito, Aedes albopictus, is more widespread and is capable of transmitting Zika, although not very efficiently.
"Countries in Southern Europe, including France and Italy, need to be especially vigilant and it's important that holidaymakers follow public health advice while abroad, including taking all the necessary precautions to avoid getting bitten.
"This is especially so for pregnant women, or women planning to become pregnant, travelling to areas where there is Zika, as there is now a proven link with microcephaly and other birth defects."