Boris Johnson has been taken to hospital for tests 10 days after testing positive for coronavirus.
According to Downing Street, The Prime Minister was still carrying a high temperature and the move was described as a 'precautionary step'.
He remains in charge of the government and urged people to follow its social distancing advice.
A spokeswoman said: "On the advice of his doctor, the Prime Minister has tonight been admitted to hospital for tests.
"This is a precautionary step, as the Prime Minister continues to have persistent symptoms of coronavirus 10 days after testing positive for the virus.
"The Prime Minister thanks NHS staff for all of their incredible hard work and urges the public to continue to follow the Government's advice to stay at home, protect the NHS and save lives."
Mr Johnson is understood to be in an NHS hospital in London where he will stay for "as long as needed".
Foreign Secretary Dominic Raab is likely to chair the daily Covid-19 meeting on Monday morning for ministers and officials, which is usually led by the PM.
Mr Johnson announced on March 27 that he had tested positive for Covid-19 and was self-isolating with "mild symptoms" including a high temperature and persistent cough.
He has shared several video updates from his Number 11 flat since his diagnosis, and stepped outside to join the nationwide clap for NHS staff on Thursday evening.
Labour leader Sir Keir Starmer tweeted: "Wishing the Prime Minister well and a speedy recovery."
According to the latest figures from Public Health England, there are now 47,806 confirmed cases of coronavirus across the UK.
And 4,934 people have now died after testing positive for Covid-19.
