Prime Minister Boris Johnson has tested positive for coronavirus, Downing Street has said.
Mr Johnson has mild symptoms and will self-isolate in Downing Street.
"He was tested for coronavirus on the personal advice of England's chief medical officer, Professor Chris Whitty," a statement said.
He will still be in charge of the government's handling of the crisis, the statement added.
The test was carried out at Number 10 by NHS staff.
In a tweet, Mr Johnson said: "Over the last 24 hours I have developed mild symptoms and tested positive for coronavirus. I am now self-isolating, but I will continue to lead the government's response via video-conference as we fight this virus.
"Together we will beat this."
Mr Johnson was last seen on Thursday night, as he clapped outside No 10 as part of a nationwide gesture to thank NHS staff.
There are more than 11,600 confirmed cases of coronavirus in the UK, and 578 people have died.