LONDON (AP) — British Prime Minister Boris Johnson spent the night in the intensive care unit of a London hospital with the new coronavirus, but is not on a ventilator, a senior government minister said today, as pressure grew on the government to release more details of Johnson’s condition.

Johnson was admitted to St. Thomas’ Hospital late Sunday, 10 days after he was diagnosed with COVID-19, the first major world leader to be confirmed to have the virus. He was moved to the ICU Monday after his condition deteriorated.

Cabinet Office Minister Michael Gove said Johnson is being given oxygen but “the prime minister is not on a ventilator.”

He said he did not know whether the prime minister had pneumonia, which often develops in patients hit hardest by the coronavirus.

Gove said Johnson is “receiving the very, very best care from the team at St Thomas’ and our hopes and prayers are with him and with his family.”

“We’re desperately hoping that Boris can make the speediest possible recovery,” said Gove, who is in isolation at home after a family member showed mild coronavirus symptoms.

Johnson’s fiancee, Carrie Symonds, who is pregnant, is herself recovering from coronavirus symptoms.

Britain has no official post of deputy prime minister, but Foreign Secretary Dominic Raab has been designated to take over temporarily.

“The government’s business will continue,” Raab said late Monday. He said Johnson had asked him “to deputize for him where needed in driving forward the government’s plans to defeat coronavirus.”

The deterioration of Johnson’s health took many in Britain by surprise. On Monday afternoon he tweeted that he was in good spirits and thanked the National Health Service for taking care of him and others with the disease.

The government was facing calls today to be more transparent about Johnson’s condition amid claims they had underplayed its seriousness.It’s not common for the health details of British prime ministers to be made public, except at times of crisis. Even then, information has sometimes been scanty. When Winston Churchill suffered a debilitating stroke in 1953, the government kept it secret until Churchill recovered.

Johnson had been quarantined in his Downing Street residence since being diagnosed with COVID-19 on March 26.

He continued to work throughout his illness, to the concern of some of his colleagues. With the U.K. still approaching the peak of the coronavirus outbreak, and the government facing accusations that it did not act soon enough to put the country into lockdown, Johnson and his ministers are under intense pressure.