All direct flights from coronavirus-hit Wuhan in China to Heathrow will be subjected to enhanced monitoring, the Government has announced.
The Department of Health and Social Care (DHSC) said precautionary measures are being put in place after cases of the virus spread to other parts of the world.
There are three direct flights a week from Wuhan in China to Heathrow Airport.
Under the new measures, the captain of each flight will tell passengers during landing to let a flight attendant know if they feel unwell.
These details will then be passed on to public health teams at the airport who will carry out further checks.
There are no plans to introduce blanket temperature screening of all passengers, a spokesman for the DHSC said, as the incubation period for the illness can be as long as five days.
But all passengers on each flight will be given a leaflet explaining how they can seek help if they become unwell while in the UK.
A statement from the DHSC said: “We have been carefully monitoring the situation in Wuhan for some time and are ready to put in place proportionate, precautionary measures.
“From today, enhanced monitoring will be in place from all direct flights from Wuhan to the UK.
“The enhanced monitoring package includes a number of measures that will help to provide advice to travellers if they feel unwell.
“For those travelling back directly from Wuhan, this includes a port health team who will meet each direct flight aircraft to provide advice and support to those that feel unwell.”
The move comes as Public Health England (PHE) upgraded the risk to the UK population from coronavirus from “very low” to “low”.
Dr Nick Phin, deputy director of the National Infection Service at PHE, said: “This is a new and rapidly evolving situation where information on cases and the virus is being gathered and assessed daily.
“Based on the available evidence, the current risk to the UK is considered low.
“If you are travelling to Wuhan, you should maintain good hand, respiratory and personal hygiene and should avoid visiting animal and bird markets or people who are ill with respiratory symptoms.
“Individuals should seek medical attention if they develop respiratory symptoms within 14 days of visiting Wuhan, either in China or on their return to the UK.
“They should phone ahead before attending any health services and mention their recent travel to the city.”
Chinese authorities have told people to stop travel into and out of Wuhan.
There have been 440 confirmed cases, according to official Chinese figures, and nine people have died.
A handful of cases have been identified abroad, including in Japan and the US, but there have been no reported cases in the UK.
On Wednesday, the World Health Organisation (WHO) looks set to declare an international public health emergency over the virus.
Professor Neil Ferguson, director of the Medical Research Centre for Global Infectious Disease Analysis, said the estimated number of people infected with coronavirus in Wuhan is around 4,000, with a range between 1,000 and 9,700.
Asked whether it was possible the virus had already reached the UK, Prof Ferguson said he could not rule it out.
He said: “We can’t rule out that possibility.
“Border screening, and in this case, in the UK, alerting the health system is not 100% foolproof – there could be a mild case.
“The UK is not a major destination of visitors travelling out of Wuhan around the world though.
“So I would say it was unlikely, but can’t be completely sure.”
Prof Ferguson said “trying to identify people who are sick coming off a plane will only identify, if you’re lucky, people who will have fever coming off a plane.
“If somebody was infected two days before they travelled, they will arrive without any symptoms at all.
“That’s why it’s essential that actually the entire… health system is alert to the possibility of imported cases.”
A spokesman for Heathrow said: “The welfare of our passengers and colleagues is always our main priority and we are working with the Government to support the implementation of enhanced monitoring measures as a precaution.”