A twentieth person has tested positive for the novel coronavirus in what is believed to be the first case of transmission within the UK.
The virus was passed on within the UK, Chief Medical Officer for England Professor Chris Witty said.
The patient is in isolation in a London hospital this evening.
Public Health England has confirmed the patient is a Surrey resident.
Prof Whitty said: "The virus was passed on in the UK.
"It is not yet clear whether they contracted it directly or indirectly from an individual who had recently returned from abroad.
"This is being investigated and contact tracing has begun. The patient has been transferred to a specialist NHS infection centre at Guy's and St Thomas'.
The patient has not been identified by health bosses.
The Guardian reported earlier today that a Surrey GP was feared to have the illness, raising fears for the patients he has been seeing.
The newspaper reported the potential case had prompted alarm among health officials trying to curtail the spread of the virus as they launched an urgent investigation to trace his patients.
However PHE said the latest confirmed patient in Surrey was not a doctor.
Dr Alison Barnett, Centre Director at Public Health England South East, said: "Public Health England is contacting people who had close contact with a confirmed case of COVID-19.
"One of the latest cases is a resident of Surrey and we're working closely with NHS colleagues in that area as well as Surrey County Council to manage the situation and help reduce the risk of further cases."
She continued: "Close contacts will be given health advice about symptoms and emergency contact details to use if they become unwell in the 14 days after contact with the confirmed case.
"This tried and tested method will ensure we are able to minimise any risk to them and the wider public."
The total number of cases in England is now 18.
Following confirmed cases in Northern Ireland and Wales, the total number of UK cases is 20.
The Department of Health and Social Care (DHSC) said in a statement that the virus was passed on in the UK but the original source of the virus was "unclear".
It added that there was no "immediately identifiable link" to overseas travel.
The DHSC added: "The virus was passed on in the UK but the original source of the virus is unclear at this stage.
"We do not currently have complete understanding of the chain of transmission in this case, but there is no immediately identifiable link to overseas travel.
"Given the recent increases in international case numbers, especially Europe, it is highly likely that we will soon see some instances of community transmission in the UK."
Wales today announced its first case of coronavirus - a woman who had travelled back from virus-hit northern Italy, following the pattern so far of cases being traced to people returning from travel.
This morning the DHSC had also announced that two Brits had contracted the virus while in Iran.
Surrey County Council's interim director of public health Ruth Hutchinson released a statement following the announcement of the twentieth diagnosis.
It said: "Surrey County Council is working with health colleagues to do everything we can to stop the virus spreading and ensure the people of Surrey are protected.
"Good hygiene is the best prevention and there are some simple steps you can take to protect you and your family by washing your hands regularly and thoroughly, and if you cough, cover your mouth and nose with a tissue."
The announcement confirming the latest diagnosis comes after a British man became the sixth person to die on board a cruise ship quarantined off the coast of Japan.
His death on board the virus-hit Diamond Princess was confirmed earlier today.
His name and age has not yet been released.
Sky News tonight reported the British man who died was in his 70s and did not live in the UK.
He was one of 78 Brits aboard the cruise liner carrying 3,700 which had to be quarantined in Yokohama.
The World Health Organisation has upgraded the global risk of the killer coronavirus to 'very high'.
This comes as the virus' spread across the world increases at pace.
Director general of the WHO, Tedros Adhanom Ghebreyesus, released a statement today urging countries to stop transmission in between patients within their borders.
His statement said: "Our epidemiologists have been monitoring these developments continuously, and we have now increased our assessment of the risk of spread and the risk of impact of Covid-19 to very high at a global level."
He added: "What we see at the moment are linked epidemics of Covid-19 in several countries, but most cases can still be traced to known contacts or clusters of cases.
"We do not see evidence as yet that the virus is spreading freely in communities.
"As long as that's the case, we still have a chance of containing this coronavirus, if robust action is taken to detect cases early, isolate and care for patients and trace contacts.
"As I said yesterday, there are different scenarios in different countries, and different scenarios within the same country. The key to containing this coronavirus is to break the chains of transmission."
The world's research community is in a race to find ways to prevent the spread of the virus.
The WHO said today 20 vaccines in development globally and "several therapeutics are in clinical trials".