Prime Minister Boris Johnson has tested positive for coronavirus and says he has a "temperature" and "persistent cough".
Downing Street said he started experiencing "mild symptoms" on Thursday.
The PM said he will "continue to lead the Government's response via video-conference as we fight this virus".
Speaking in a video released on his Twitter page, Mr Johnson said: "I am working from home and self-isolating and that's entirely the right thing to do.
"But, be in no doubt that I can continue, and thanks to the wizardly of modern technology, to communicate with all my top team to lead the national fightback against coronavirus.
"We are going to beat it and we are going to beat it together. Stay at home, protect the NHS and save lives".
A spokeswoman for Downing Street confirmed the test was carried out in No 10 by NHS staff.
It is not known whether he is staying with his fiancee, Carrie Symonds, who is several months pregnant.
Health Secretary Matt Hancock has also tested positive for COVID-19 and has said he will be self-isolating for the next week.
Earlier in the week, it was announced that the Prince of Wales was also suffering from “mild symptoms” of coronavirus.
Cover image: Boris Johnson at a coronavirus press briefing earlier this week (Picture: PA).