More than a dozen people in the UK have been tested for the new strain of coronavirus, Public Health England has said.
Five people have tested negative while nine others are waiting for results.
In Scotland, where five people were tested, an incident team has been set up to deal with the health threat.
Globally, there are more than 800 confirmed cases of the virus, which has killed 26 people in China. Authorities there are battling to contain it.
Public Health England's (PHE) announcement that 14 people in the UK had been tested came on Thursday night, but they did not give details of where the cases were.
Four of the five people being tested in Scotland were believed to be Chinese, Downing Street said.
Meanwhile, one man was treated in Belfast for symptoms associated with coronavirus.
All the patients had been in Wuhan – the Chinese city where the virus first broke out – in the last 14 days.
Prime Minister Boris Johnson's spokesman said the tests were "purely precautionary".
Prof Paul Cosford, medical director at PHE, told BBC Breakfast "we won't be surprised" if people returned from China to the UK with the infection.
He said: "These are early days yet with this virus. The vast majority of people who are infected do seem to be getting better.
"The people who have done particularly badly, and sadly died, they seem to be people who have other conditions that might make them more likely to suffer badly with this virus."
Health Secretary Matt Hancock said there was an "increased likelihood" of cases of the new coronavirus occurring in the UK, but "we are well prepared" to deal with them.
In a statement to the House of Commons on Thursday, Mr Hancock said that it was a "rapidly developing situation and the number of deaths and the number of cases is likely to be higher than those that have been confirmed so far and I expect them to rise further".
He told MPs: "The chief medical officer has revised the risk to the UK population from 'very low' to 'low' and has concluded that while there is an increased likelihood that cases may arise in this country, we are well prepared and well equipped to deal with them."
He added: "The UK is one of the first countries to have developed a world-leading test for the new coronavirus."
What should you do if you think you have the virus?
Public Health England is advising anyone who has been to Wuhan within the past 14 days and has developed respiratory symptoms to phone NHS 111.
Those symptoms include a cough, a sneeze, shortness of breath, or a fever.
People who are concerned should phone ahead before going to any medical facility and mention their recent travel to the city.
PHE also advises anyone travelling to China to maintain good hand, respiratory and personal hygiene, and avoid visiting animal and bird markets or people who are ill with respiratory symptoms.
The agency is currently not advising people to wear face masks.
Wuhan – which has a population of 11 million people – has gone into lockdown, with authorities suspending planes and trains in and out of the city.
Beijing, Hong Kong and Macau have also cancelled some major festivities to prevent large crowds gathering together, as the country prepares to celebrate the Lunar New Year.
On Thursday, Vietnam and Singapore joined the list of countries where the virus had spread. Cases have also been reported in Thailand, the US, Taiwan, Japan and South Korea.
Authorities around the world have announced screening measures for passengers from China.
In response to the outbreak, the Foreign Office has advised against all but essential travel to Wuhan.
The UK is monitoring direct flights arriving from China as a precaution.
Passengers are receiving leaflets and advice on what to do if they fall ill, and a health team is available at Heathrow Airport to check for symptoms.