Prime Minister Boris Johnson has been admitted to hospital for tests, 10 days after testing positive for coronavirus, Downing Street has said.
He "continues to have persistent symptoms of coronavirus", a spokeswoman said - including a high temperature.
It was described as a "precautionary step" taken on the advice of his doctor.
The prime minister remains in charge of the government and urged people to follow its social distancing advice.
"On the advice of his doctor, the prime minister has tonight been admitted to hospital for tests," the spokeswoman said.
"This is a precautionary step, as the prime minister continues to have persistent symptoms of coronavirus ten days after testing positive for the virus."
She added: "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 has worked from home since it was announced that he had tested positive for coronavirus on 27 March.
He chaired a coronavirus meeting via video-link on Friday morning.
He was last seen in public applauding the NHS and other key workers from his flat in Downing Street on Thursday.