In an interview with the Sun on Sunday, the prime minister said at one point it was "50-50" whether he would be put on a ventilator.

"That was when it got a bit… they were starting to think about how to handle it presentationally," he said.

"It was a tough old moment, I won't deny it," I told the paper.

He said he knew at the time that doctors had devised a plan in the event of his death.

"They had a strategy to deal with a 'death of Stalin'-type scenario," he said, in reference to the former Soviet Union leader, Joseph Stalin.

Mr Johnson said he was given "liters and liters of oxygen" to keep him alive and credited his recovery to "wonderful, wonderful nursing".

"I get emotional about it... But it was an extraordinary thing."

Mr Johnson was diagnosed with coronavirus on 26 March and was admitted to London's St Thomas' Hospital 10 days later. The following day, he was moved to intensive care.

"It was hard to believe that in just a few days my health had deteriorated to this extent," he said.