The UK Prime Minister Boris Johnson has not been diagnosed with pneumonia, a Downing Street spokesman said Tuesday.

"The prime minister has been stable overnight and remains in good spirits," said the spokesman in a statement.

Johnson is still in intensive care and receiving "standard oxygen treatment" but is not on a ventilator and does not have pneumonia.

In the interim, he has asked Foreign Secretary Dominic Raab to deputize, Downing Street said.

The 55-year-old was moved to intensive care on Monday after his COVID-19 symptoms worsened. He was admitted on Sunday night, 10 days after testing positive for COVID-19.