Boris Johnson has been moved to intensive care after his condition worsened, Downing Street has said.
The Prime Minister was taken to St Thomas Hospital in London on Sunday night.
10 days after he tested positive for the coronavirus.
Mr Johnson was admitted as a precaution but his health has now deteriorated.
The prime minister has now asked Foreign Secretary Dominic Raab to deputise for him “where necessary”.
A Number 10 spokesman said: “Over the course of this afternoon, the condition of the prime minister has worsened and, on the advice of his medical team, he has been moved to the intensive care unit at the hospital.
“The prime minister has asked Foreign Secretary Dominic Raab, who is the First Secretary of State, to deputise for him where necessary.
“The prime minister is receiving excellent care, and thanks all NHS staff for their hard work and dedication.”