BORIS Johnson was admitted to hospital on Sunday night for tests, 10 days after testing positive for coronavirus.
The PM “continues to have persistent symptoms of coronavirus” Downing Street said.
It was described as a “precautionary step” taken on the advice of his doctor.
Boris Johnson remains in charge of the government, but Dominic Raab is expected to chair a coronavirus meeting this morning.
In a statement, a Downing Street spokeswoman said: “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.”
This comes after The Queen said in a televised speech on Sunday: “better days will return” and the UK “will succeed” in its fight against coronavirus, in a rallying message to Brits and the Commonwealth.
Her Majesty thanked people for following government rules to stay at home and praised those “coming together to help others”.
She also thanked key workers, saying “every hour” of work “brings us closer to a return to more normal times”.