Facebook is closing its London offices after an employee was diagnosed with coronavirus.
The company will be shutting three of its offices in the UK capital until Monday after the employee who is based in Singapore visited between 24-26 February.
Staff are being told to work from home as a deep clean takes place.
Facebook is thought to have around 3,000 employees in London.
It is not clear how many people had come into contact with the employee who has tested positive, but Facebook said it had been in contact with them all.
These people have been told to self-isolate and watch out incase they develop any symptoms.
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A spokesperson for Facebook told Sky News: "An employee based in our Singapore office who has been diagnosed with COVID-19 visited our London offices 24-26 February 2020.
"We are therefore closing our London offices until Monday for deep cleaning and employees are working from home until then."
There are now 163 coronavirus cases in the UK after 47 more people were diagnosed in the last 24 hours in the biggest day-on-day increase so far.
Yesterday a woman in her 70s, who also had pre-existing medical conditions, became the first to die after catching the flu-like virus.
A man in his 80s, who had underlying health conditions, is feared to have become the second person to die in the UK.
Scotland reported five more cases and two British Airways baggage handlers, who work at Heathrow Airport, have tested positive for the killer bug.
As of 7am on this morning, 20,338 people have been tested in the UK, with 163 confirmed as positive and 20,175 negative.
The UK's latest cases emerged as Boris Johnson pledged a further £46million for research into a vaccine and rapid diagnostic tests.
The Prime Minister announced the funding during a tour of a Bedfordshire laboratory, where British scientists are working on a quick and cheap way to diagnose coronavirus.
Mr Johnson said that it looked like the UK will face a "substantial period of disruption" due to the coronavirus.
He said: "It looks like there will a substantial period of disruption where we have to deal with this outbreak."
The number of people infected with coronavirus across the world surpassed 100,000 today as the outbreak reached more countries.
An increasing number of people faced a new reality as many were asked to stay home from work, schools were closed, large gatherings and events were cancelled, stores cleared of staples like toiletries and water, and face masks became a common sight.
The outbreak has killed more than 3,400 people and spread across more than 90 nations, with six countries reporting their first cases on Friday.
