Four more people in the UK have tested positive for coronavirus, bringing the total number to eight.
It comes as the government announced new powers to keep people in quarantine to stop the spread of the virus.
In order to do this the Department of Health has described the virus as a “serious and imminent threat” to public health. The overall risk level to the UK remains “moderate”.
There have been more than 40,000 cases of the virus globally, mostly in China.
The total number of deaths in China is now 908 – but the number of newly-infected people per day has stabilised.
Officials have told the BBC the announcement uses legal language to keep people who have travelled from Wuhan in quarantine in Milton Keynes and the Wirral, the BBC’s health editor Hugh Pym said.
A Department of Health spokesman said: “We are strengthening our regulations so we can keep individuals in supported isolation for their own safety and if public health professionals consider they may be at risk of spreading the virus to other members of the public.
“This measure will rightly make it easier for health professionals to help keep people safe across the country.”
The BBC’s political correspondent Iain Watson said the new measures were announced because a passenger on the first UK flight from Wuhan, who is currently being held in quarantine on the Wirral, “is threatening to abscond”.
“Currently the regulations are not strong enough to stop him leaving before the 14-day period is up so they brought in these new regulations to try and compel him to stay put,” he told BBC Radio 4’s Today programme.
On Sunday, around 200 British and foreign nationals arrived on the second and final flight chartered to the UK from Wuhan by the Foreign Office. Evacuees were taken to a Milton Keynes conference centre for 14 days of quarantine.
Meanwhile, a fourth person was diagnosed with coronavirus in the UK on Sunday, having caught the virus in France.
Why have they issued this advice?
Tackling the coronavirus threat has taken the government into uncharted territory. Quarantining hundreds of British citizens for two weeks has never been done on this scale in modern times.
Whitehall sources say the latest Department of Health announcement on the virus threat covers the tightening of some regulations to help enforce quarantine powers.
This gives legal underpinning to the quarantining of people back from Wuhan in Milton Keynes and the Wirral.
They all signed contracts committing to the 14-day isolation but it’s understood that more rigorous regulations are needed to ensure people stay the course.
This is not a ramping up in official warnings to the wider public. The language used in the official release describing an “imminent threat” was over dramatic and confusing and probably there only for obscure legal reasons.
The actual threat level announced by Public Health England a couple of weeks ago remains moderate.
In a statement on Monday, Health Secretary Matt Hancock said Arrowe Park Hospital, on the Wirral, and Kents Hill Park conference centre, in Milton Keynes, have been designated as “isolation” facilities in the UK.
A statement on the Department of Health website said: “In accordance with Regulation 3, the Secretary of State declares that the incidence or transmission of novel coronavirus constitutes a serious and imminent threat to public health, and the measures outlined in these regulations are considered as an effective means of delaying or preventing further transmission of the virus.”
As of 2pm on Sunday, the Department of Health said a total of 795 coronavirus tests were concluded in the UK, with four testing positive and 791 confirmed negative.
Confirming the fourth UK case on Sunday, chief medical officer for England Prof Chris Whitty said the patient, who is being treated at the Royal Free Hospital in London, is “a known contact of a previously confirmed UK case, and the virus was passed on in France”.
The third UK case is a British man who caught coronavirus in Singapore and was transferred to St Thomas’ Hospital in London on Thursday, from Brighton.
Five British nationals who have tested positive in France were diagnosed after they came into contact with him, according to the French health ministry.
Meanwhile, a British man in Majorca has also been diagnosed with coronavirus, while his wife and two daughters tested negative.
The family said they had been in contact with a person who tested positive for coronavirus in France, the government in the Balearic Islands said.
The new virus was first reported in Wuhan, the capital of Hubei province. The city of 11 million has been in lockdown for weeks.
The outbreak was declared a global emergency by the WHO on 30 January.