The death toll from COVID-19 in the United Kingdom rose to 28,205 on May 3, falling just short of Italy which has so far had the world's second most deadly outbreak of the disease after the United States.

The United States has had 66,224 deaths, followed by 28,710 in Italy, 28,205 in the UK and 25,100 in Spain, according to the Coronavirus Resource Center of Johns Hopkins University.

As Britain shadows Italy for the grim status of being the worst-hit country in Europe, Prime Minister Boris Johnson is facing criticism from opposition parties who say his government stumbled in the early stages of the outbreak.

Johnson initially resisted introducing a lockdown to restrict economic and public activity, but changed course when projections showed a quarter of a million people could die.

Johnson himself battled COVID-19 last month in London's St Thomas' Hospital where he received oxygen treatment and spent three nights in intensive care.

He told The Sun newspaper the British government had a contingency plan for his death as his condition deteriorated.

"The doctors had all sorts of arrangements for what to do if things went badly wrong," Johnson said of his COVID-19 battle. "The bloody indicators kept going in the wrong direction."

"It was a tough old moment, I won't deny it. They had a strategy to deal with a 'death of Stalin'-type scenario," Johnson told The Sun.

After Johnson was discharged, St Thomas' Hospital management said it was glad to have cared for the prime minister, but gave no details about the gravity of his illness beyond stating that he was treated in intensive care.

Johnson and his fiancee, Carrie Symonds, on Saturday announced the name of their newly born son as Wilfred Lawrie Nicholas, partly as a tribute to two of the intensive care doctors who they said had saved Johnson's life.

The prime minister returned to work on Monday, telling the nation that people around the world were looking at the UK's "apparent success."

He said the country is over the peak but it is still too early to relax the lockdown he imposed on March 23 because there could be a second peak that he fears might overwhelm hospitals.

(With input from Reuters)