LONDON — Britain’s Treasury chief says Prime Minister Boris Johnson’s condition is improving in the intensive care unit of a London hospital.

Rishi Sunak says Johnson has been sitting up in bed and engaging with his doctors at St. Thomas’ Hospital.

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Johnson was admitted to the hospital on Sunday, 10 days after being diagnosed with COVID-19. He was transferred to the ICU on Monday when his condition deteriorated.

Johnson’s spokesman said earlier Wednesday that the prime minister was receiving “standard oxygen treatment” and is breathing without any other assistance.

Johnson, 55, is the first world leader confirmed to have the new coronavirus.

THIS IS A BREAKING NEWS UPDATE. AP’s earlier story follows below.

LONDON (AP) — British Prime Minister Boris Johnson is “responding to treatment” but remains in intensive care with the new coronavirus, his spokesman said Wednesday, as the U.K. saw its biggest spike in deaths from the virus to date.

A shaken U.K. government sought to keep a grip on its response to the outbreak with its leader hospitalized and the number of COVID-19-related deaths approaching the peaks seen in Italy and Spain, the two countries with the greatest number of fatalities.

Britain’s confirmed death toll reached 7,097 on Wednesday, an increase of 938 from 24 hours earlier. Italy recorded 969 deaths on March 27 and Spain 950 deaths on April 2.

Not all the deaths reported each day occurred in the preceding 24 hours, and the British total only includes deaths in hospitals.

Johnson was diagnosed with COVID-19 on March 26 and still had a cough and fever 10 days later. He was admitted to St. Thomas’ Hospital in London on Sunday and moved to the ICU on Monday after his condition deteriorated. Foreign Secretary Dominic Raab is standing in for Johnson while he is hospitalized.

Johnson spokesman James Slack said the prime minister continues to receive “standard oxygen treatment” and is breathing without any other assistance.

Slack declined to provide further details of Johnson’s treatment, saying Wednesday’s update “contains all of the information which the PM’s medical team considers to be clinically relevant.”

The virus has hit people from all walks of life — including Johnson, the first world leader known to have been diagnosed with COVID-19. The 55-year-old prime minister was hospitalized with a fever and cough that persisted 10 days after he tested positive for the virus. He was moved to the ICU on Monday night after his condition deteriorated.

Johnson’s illness has unleashed a wave of sympathy for the prime minister, including from his political opponents. It has also heightened public unease about the government’s response to the outbreak, which faced criticism even with the energetic Johnson at the helm.

Britain was slower than many other European nations to close schools, shut businesses and restrict people’s movements in a bid to curb infections, and the government has struggled to meet its goal of dramatically increasing the number of individuals tested for the virus.

Britain initially restricted testing to patients in hospitals with coronavirus symptoms, but has begun testing health care workers and their families. The government has said even broader testing will be part of the country’s exit strategy from the lockdown, and has promised to test 100,000 people a day by the end of April. The current number is about 14,000 a day.

After a slow start, the government has urged the private sector to get involved. Drug makers GSK and AstraZeneca say they are setting up a lab at Cambridge University capable of performing 30,000 tests a day by the start of May.

Slack defended the government’s response.

“We took our decisions based on the best available medical and scientific advice,” he said. “We believe we acted with the right measures at the right rime.”

In Johnson’s absence, it’s unclear who would decide whether to ease nationwide lockdown measures the British government imposed on March 23 in response the worldwide pandemic.

The initial three-week period set for the restrictions expires next week, but with cases and deaths still growing, officials say it is too soon to change course.

“We need to start seeing the numbers coming down,” Health Minister Edward Argar told the BBC. “That’s when you have a sense, when that’s sustained over a period of time, that you can see it coming out of that. “

Mark Drakeford, the first minister of Wales, said it was clear “these restrictions will not end” next week.

“We will not throw away the gains we have made and the lives we have saved by abandoning our efforts just as they begin to bear fruit,” he said.

Meanwhile, officials are watching anxiously to see whether Britain’s hospitals can cope when the number of seriously ill COVID-19 patients reaches its peak. Before the outbreak, the U.K. had about 5,000 intensive care beds, and the government has been scrambling to increase that capacity.

The Nightingale Hospital — a temporary facility for coronavirus patients built in nine days at London’s vast ExCel conference center — admitted its first patients on Wednesday. It can accommodate 4,000 beds, if needed. Several other temporary hospitals are being built around the country, including a facility in Birmingham due to open Friday.

London Mayor Sadiq Khan said the city, which is the epicenter of Britain’s outbreak, had one-quarter of its existing hospital beds still available, as well as the new Nightingale hospital.

Khan was under pressure to do more to keep transit workers safe after 14 London transport staff died from the new coronavirus, including eight bus drivers.

London’s subways and buses have continued to run a reduced service to transport key workers. Khan said buses were being cleaned with antiviral disinfectant and protective screens were being installed between driver and passengers.

Anne Nyack, whose 36-year-old son Emeka Nyack Ihenacho is among the drivers who died, said drivers were still not being protected.

“They are at risk, my son was at risk, sadly he died,” she told ITV. “He was given hand sanitizer — he had no mask, no gloves, nothing.”