Chancellor of the Exchequer Rishi Sunak has revealed that Prime Minister Boris Johnson's condition is "improving" as he battles COVID-19.

The 55-year-old was admitted to St Thomas' hospital in central London on Sunday but was transferred to intensive care less than 24 hours later after his health took a turn for the worse.

Speaking at Downing Street's daily press briefing today, Sunak delivered an update on the PM's current condition.

"He is receiving excellent care from the NHS team at St Thomas'," he said. "The latest from the hospital is that the Prime Minister remains in intensive care, where his condition is improving.

"I can also tell you that he has been sitting up in bed and engaging positively with the clinical team.

"The Prime Minister is not only my colleague and my boss but also my friend and my thoughts are with him and his family."

The news comes after the government reported the highest increase in the daily death toll to date, with 938 more people losing their lives to coronavirus.