Donald Trump says the UK may be added to a list of countries hit by a US travel ban over coronavirus - as he declared the pandemic a national emergency.
The UK and Ireland were exempt when the US president announced earlier this week he would not allow people from 26 European nations in the Schengen area to come into America for 30 days.
But he has now admitted he may have to add more countries to the ban - which has now come into effect - while taking others off the list.
Eleven people have died in the UK after contracting COVID-19 , the disease caused by coronavirus, and the number of confirmed infections has reached 798 - an increase of 208 over the last 24 hours.
In other developments across the world:
Announcing the national emergency in the US, Mr Trump's move will free up a total of $50bn (£40.5bn) for state and local governments to try to combat the spread of the virus.
More than 30 people in America have died after being diagnosed with COVID-19 and there have been over 1,200 infections in 46 states.
Worldwide, the disease has infected over 138,000 people and left more than 5,000 dead.
Speaking at the White House on Friday, Mr Trump said: "We will defeat this threat. When America is tested America rises to the occasion."
He added: "This will pass."
Mr Trump indicated he himself would get tested for coronavirus "fairly soon" but said he had not shown any symptoms.
It comes after a photo reportedly taken last weekend showed him standing next to Brazilian President Jair Bolsonaro's press secretary Fabio Wajngarten, who has tested positive for COVID-19.
White House physician Dr Sean P Conley also said the president encountered a second individual last weekend who later tested positive for coronavirus.
The encounter was "low risk" and there was no need for the president to "home quarantine", Dr Conley said in a statement.
"The president's exposure to the first individual was extremely limited (photograph, handshake) and though he spent more time in closer proximity to the second case, all interactions occurred before any symptom onset," he added.
Mr Trump said he was asking hospitals to activate their emergency preparedness plans, and will give doctors "flexibility" in treating patients, as he waived federal regulations and laws.
His administration has been accused of being too slow to make coronavirus testing available.
Mr Trump said he expected up to half a million extra tests will be brought out early next week, as he announced a public-private partnership to increase capability.
He added that a Google website will help Americans work out if they need to take the test, and what drive-through testing options are available to them, including in supermarket car parks.
The president also waived interest on federally-held student loans and told the department of energy to buy oil to help producers as crude prices have plunged.
Asked about the UK possibly being included in a US travel ban, a Downing Street spokesperson said: "This is a matter for the US.
"We're not going to comment on measures taken by another country."
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By declaring the pandemic an emergency, the president has invoked a law known as the Stafford Act, which was originally introduced in 1988.
It allows the Federal Emergency Management Agency (FEMA) - part of the Department of Homeland Security - to assist state and local governments during "natural catastrophes" and co-ordinate the nation's response.
FEMA controls tens of billions of dollars in federal disaster relief funding which could be used for measures including helping to build medical facilities and transport patients.
It comes as the speaker in House of Representatives, Nancy Pelosi, announced the Democrat-controlled House would approve a coronavirus aid package.
The plan would provide free coronavirus testing and two weeks of paid sick and family leave for those affected by the disease, Ms Pelosi said.
But Mr Trump has not backed the package, making its outcome uncertain in Congress.
Ms Pelosi does not need support from the Republicans to pass legislation in the Democrat-majority House.
But it would probably not get far in the Republican-controlled Senate without bipartisan support.
The House aid package builds on an emergency $8.3bn measure approved last week.
Sky News will broadcast a special coronavirus programme at 6.30pm tonight, with experts answering your questions #AskSkyNews