British Prime Minister Boris Johnson was on Monday admitted to intensive care after being hospitalised with coronavirus, with foreign minister Dominic Raab to take over his duties “where necessary”, his Downing Street office 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,” said the Downing Street press release.

“The PM has asked Foreign Secretary Dominic Raab… to deputise for him where necessary,” it added.

The prime minister was moved in case he needed to use a ventilator, the government added.

Johnson was admitted to St Thomas’ Hospital in London on Sunday with a temperature and a cough after testing positive for coronavirus on March 27, becoming the most high-profile world leader infected with the disease that has spread rapidly across the globe.

The 55-year-old had been self-isolating in his Downing Street flat but on Sunday evening was driven to a nearby state-run hospital on the advice of his doctor.

Officials said it was a “precautionary step” but questions had earlier been raised about whether the Conservative leader could still run the country.

The British government was criticised for initially refusing to follow other European countries in requiring people to stay home as the virus spread.

And Johnson himself said in early March that he was still shaking hands with people.

But two weeks ago he ordered a nationwide lockdown and Britain is now in the grip of a serious outbreak.

Over 50,000 cases and more than 5,000 deaths have been recorded so far, with a latest daily toll of 439.

Health Secretary Matt Hancock and the heir to the throne, Prince Charles, have both been infected with coronavirus, although they have since recovered.

In response to the crisis, Queen Elizabeth II made a rare public address on Sunday night, evoking the spirit of World War II and urging Britons to stay united.

“We will be with our friends again, we will be with our families again, we will meet again,” she said.