Four more patients in England have coronavirus - doubling the total to eight - and they caught the bug from a "super spreader" now linked to 11 cases.
The three men and one woman had contact with a Brighton man who contracted the flu-like virus during a business trip to Singapore and passed it to others at a ski chalet in the French Alps.
The four, including a doctor, caught the virus on the ski trip in Contamines-Montjoie and tested positive in Brighton at the weekend.
The County Oak Medical Centre in Brighton was shut after a staff member was confirmed to have coronavirus.
Earlier, the UK Government declared the flu-like virus a "serious and imminent threat to public health", allowing it to forcibly quarantine patients.
The rare step was taken after a Briton rescued from the coronavirus epicentre in China threatened to leave an isolation block at Arrowe Park Hospital, were dozens were put in quarantine.
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Health officials are now trying to track everyone who had contact with the ski resort group and travellers who were on an Geneva-to-London easyJet flight with the Brighton man.
Staff at a pub and a secondary school pupil were told to self-isolate after having contact with him.
The middle-aged Brighton man - the first British national to contract coronavirus - was diagnosed after returning from his French Alps getaway and is being treated at St Thomas's Hospital in London.
The four new patients are in isolation at specialist NHS centres at Guy’s and St Thomas’ and The Royal Free hospitals in London.
They are three men and one woman, the Guardian reported, and one of the men is a doctor.
Professor Chris Whitty, Chief Medical Officer for England, said: “Four further patients in England have tested positive for novel coronavirus, bringing the total number of cases in the UK to eight.
“The new cases are all known contacts of a previously confirmed UK case, and the virus was passed on in France.
"Experts at Public Health England continue to work hard tracing patient contacts from the UK cases. They successfully identified these individuals and ensured the appropriate support was provided.
“The patients have been transferred to specialist NHS centres at Guy’s and St Thomas’ and The Royal Free hospitals, and we are now using robust infection control measures to prevent further spread of the virus.
"The NHS is extremely well prepared to manage these cases and treat them, and we are working quickly to identify any further contacts these patients have had."
Dr Nick Phin, Deputy Director, National Infection Service, Public Health England, said: “These new cases are all closely linked and were rapidly identified through Public Health England’s comprehensive contact tracing approach and tested quickly.
"Our priority is speaking to those people who have had close and sustained contact with confirmed cases so that we can advise them on what they can do to limit the spread of the virus.”
According to French officials, the Brighton man was in Singapore for a conference between January 20 and 23 and stopped in Contamines-Montjoie, close to Geneva, on January 24.
He stayed at a chalet for four days before returning to Britain.
On Saturday, French officials announced that five Britons - four adults and a boy - who also stayed at the chalet had tested positive for the virus.
Brit Bob Saynor, who owns the six-bedroom chalet and recently moved to the Alps from Hove, and his nine-year-old son were among the five.
Two primary schools attended by Mr Saynor's son have been shut by French officials.
A fifth person who had contact with the Brighton man in France was diagnosed with coronavirus in the UK on Sunday and is also at the Royal Free Hospital.
A British dad-of-two, who lives in Majorca, where he tested positive, has also been linked to the group, while his wife and daughters tested negative.
SARS-like coronavirus has now killed more than 900 people and infected more than 40,000 others while spreading around the world following an initial outbreak in the central Chinese city of Wuhan in December.
The latest news has caused a scare in Brighton and Hove in East Sussex, where the "super spreader" had visited a pub and other places following his return from Singapore and France.
Worried locals were snapping up face masks, with a number of shops saying they had quickly sold out.
A spokesman for the Grenadier pub in Hove told the Argus that the infected businessman visited between 7pm and 9pm on February 1.
He said: “We have had an incident where a man has come into the pub who has since been confirmed as having coronavirus.
“Any staff working that day have been put in self-isolation.”
The pub said it remained open after being advised by Public Health England there was a "minimal ongoing risk of infection" to punters and staff.
A pupil at Portslade Community Academy in Brighton was advised to self-isolate at home after being in contact with the same man.
On February 2, the day after visiting the pub, the businessman called NHS 111 for advice for his symptoms and then went by arrangement to the Royal Sussex County Hospital to be tested. His case was confirmed on February 6.
Health officials are trying to find and test people who had contact with the entire group, including the "super spreader" who flew from Geneva to Gatwick on January 28.
An easyJet spokeswoman said: "EasyJet has been notified by the public health authority that a customer who had recently travelled on one of its flights has since been diagnosed with the coronavirus.
"Public Health England is contacting all passengers who were seated in the vicinity of the customer on flight EZS8481 from Geneva to London Gatwick on 28 January to provide guidance in line with procedures.
"As the customer was not experiencing any symptoms, the risk to others on board the flight is very low.
"We remain in contact with the public health authorities and are following their guidance.
"The health and well-being of our passengers and crew is the airline's highest priority.
"All of the crew who operated have been advised to monitor themselves for a 14-day period since the flight in line with Public Health England advice. Note this happened 12 days ago and none are displaying any symptoms."
The Brighton man caught the virus while attending a conference at the Grand Hyatt hotel in Singapore, attended by 15 Singaporeans and 94 foreigners.
UK firm Servomex, a global gas analysis company, hosted the conference, Singaporean media reported.
The other two people who have tested positive for coronavirus in the UK are Chinese nationals - a University of York student and a family member who were staying at a hotel in York.
Both were transferred to Newcastle's Royal Victoria Infirmary.
A suspected case was reported in Dover, Kent, on Monday.
Health minister Matt Hancock declared the virus "a serious and imminent threat to public health", a step that gives the government more powers to isolate people.
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."
It is understood that the decision to declare coronavirus a "serious and imminent threat to public health" was in response to one of the Britons who returned from Wuhan attempting to leave isolation.
A Government source told PA "there was someone who was threatening to abscond from Arrowe Park" despite all the Britons who returned on the first evacuation flight on January 31 signing a contract agreeing to a 14-day quarantine period.
In response to concerns about whether those contracts were legally enforceable, the new action was taken to ensure that individuals can be kept in supported isolation.
"The transmission of coronavirus would represent a serious and imminent threat so to prevent that we are taking action to enforce isolation of certain individuals," the source said.
Arrowe Park Hospital in the Wirral and Kents Hill Park in Milton Keynes have been designated as isolation facilities.
Kents Hill Park is hosting more than 100 Britons who returned from Wuhan on Sunday on the second and final repatriation flight chartered by the Foreign Office. They will spend two weeks in quarantine.
Downing Street insisted that the NHS was able to cope with the coronavirus outbreak.
The Prime Minister's official spokesman said: "We are well prepared for UK cases and have robust infection control measures in place to respond immediately, using the tried-and-tested procedures to prevent further spread and the NHS is extremely well-prepared and used to managing infections."
In Japan, health officials announced that a second Briton on the quarantined Princess Diamond cruise ship had tested positive for coronavirus.
Lorry driver Alan Steele, 58, from Wolverhampton, had previously been diagnosed despite showing no symptoms. He was on his honeymoon with his wife Wendy.
He wrote on Facebook that he could be released from a hospital in Yokohama as early as Friday if his next test results come back negative.
Officials said 136 passengers and crew had now been confirmed as carrying the disease.
The death toll from the epidemic rose to 908, all but two in mainland China, as 97 more fatalities were recorded - the largest number in a single day since the outbreak was detected in Wuhan, where the virus was passed to humans at a market selling live animals and illegal wildlife.
More than 40,000 others - most of them in China - have been infected.
The virus has spread to at least 27 countries and territories, according to a Reuters count based on official reports, infecting more than 330 people.
The two deaths outside mainland China were in Hong Kong and the Philippines.
The death toll from the outbreak has now surpassed that of another coronavirus, Severe Acute Respiratory Syndrome (SARS), which brought a global epidemic in 2002/2003.
Alarm over the coronavirus is driven by its rapid spread and the fact that infectious disease experts cannot yet know how deadly or contagious it is.
The ‘super spreader’
January 20-23: A Brighton man attends a business conference in Singapore, where he contracts coronavirus.
January 24-28: The businessman arrives in Contamines-Montjoie in the French Alps and stays at a chalet owned by a fellow Brit. French health ministry officials say he had contact with at least 11 Britons at the chalet.
January 28: The Brighton man returns to the UK on an easyJet flight from Geneva, Switzerland, to London Gatwick.
February 1: The man visits the Grenadier pub in Hove, among other places, following his return from France.
February 2: After developing symptoms at some point, the man calls NHS 111 for advice and goes by arrangement to the Royal County Sussex Hospital in Brighton to be tested for coronavirus.
February 6: The man’s case is confirmed and he is treated at St Thomas’s Hospital in London. His is the third case in the UK (joining two Chinese nationals) and he is the first British citizen to contract the potentially deadly bug.
February 8: Five British nationals - four adults and a nine-year-old boy - who had contact with the man at the chalet test positive for the virus in France.
February 9: A British dad living in Majorca tests positive after having contact with the Brighton businessman in France. The expat's wife and two daughters test negative.
February 9: A person who had contact with the Brighton man in France is confirmed to be carrying the virus and is treated at the Royal Free Hospital in London. The patient is the UK's fourth confirmed case.
February 10: Four more people in the UK are confirmed to have the disease after having contact with the businessman at the ski resort in France. It brings the total number of cases in the UK to eight.
