Flowers from the Pakistan Embassy were delivered to 10 Downing Street in central London, as Britain's Prime Minister Boris Johnson is receiving treatment in intensive care at St Thomas' Hospital with symptoms of the novel coronavirus.

The flowers were delivered by a Pakistan High Commission staffer to an officer at the 10 Downing Street.

Meanwhile, Johnson spent a second night in intensive care battling the coronavirus which has infected more than 55,000 across the country and killed nearly 6,200.

“He stayed at work for you... now pray at home for him,” The Sun tabloid splashed across its front page Wednesday while the Daily Express said: “Boris 'will pull through'.”

Deputising for Johnson, Foreign Secretary Dominic Raab said he was "confident he'll pull through, because if there's one thing I know about this prime minister, he's a fighter and he'll be back, leading us through this crisis in short order".

In an update Tuesday evening, the prime minister's spokesman said his "condition is stable and he remains in intensive care for close monitoring."

He earlier said the 55-year-old Conservative leader was receiving "standard oxygen treatment and breathing without any other assistance" and had not required a ventilator.

Johnson is the most high-profile government leader to become infected with COVID-19 and messages of support flooded in from across Britain and the world.

He was admitted to intensive care on Monday evening after spending Sunday night in hospital following concerns he still had a cough and high temperature 10 days after being diagnosed with COVID-19.