UK 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."
The prime minister is expected to stay in hospital overnight, the BBC's political editor said.
Johnson has worked from home since it was announced that he had tested positive for coronavirus on 27 March.
He was last seen in public applauding the NHS and other key workers from his flat in Downing Street on Thursday evening, and chaired a coronavirus meeting via video-link on Friday morning.
Johnson posted a Twitter video on Friday in which said he was still displaying minor symptoms.
Another quick update from me on our campaign against #coronavirus.— Boris Johnson #StayHomeSaveLives (@BorisJohnson) April 3, 2020
You are saving lives by staying at home, so I urge you to stick with it this weekend, even if we do have some fine weather.#StayHomeSaveLives pic.twitter.com/4GHmJhxXQ0
"Although I'm feeling better and I've done my seven days of isolation, alas I still have one of the symptoms, a minor symptom, I still have a temperature," a weary-looking Johnson said in the video.
Carrie Symonds, Johnson's 32-year-old pregnant fiancee, said on Saturday she was on the mend after having symptoms of the coronavirus.
Britain's health minister Matt Hancock had also tested positive for the virus and returned from self-isolation on Thursday to host the daily Downing Street news conference.
The government's chief medical adviser, Prof Chris Whitty, has also had to self-isolate after showing symptoms.
Last month, the prime minister's spokesman said if the prime minister was unwell and unable to work, Foreign Secretary Dominic Raab, as the first secretary of state, would stand in.
- BBC / Reuters