British Prime Minister Boris Johnson is a "fighter" who will be back at the helm to lead the country through the coronavirus pandemic, Foreign Secretary Dominic Raab says.
Raab said the Prime Minister - who is in intensive care with coronavirus - remained "in good spirits" and had not received any mechanical ventilation but has had "standard oxygen treatment".
Speaking at today's Downing Street briefing Raab added: "He's not just the Prime Minister, he's not just our boss, he is also a colleague and he is also our friend. All of our thoughts and prayers are with the Prime Minister at this time."
It comes as the curve of new coronavirus cases in the UK could be flattening, Sir Patrick Vallance, the chief scientific advisor has said.
The number of new hospitalisations has seen a "steady increase" indicating it could be "flattening off".
The death toll in the UK reached 6159 today, after 786 more people died in hospital after testing positive for the coronavirus, the Department of Health has said.
If Johnson's condition changed, the Government would make an official statement, Cabinet Office minister Michael Gove said.
"He's not on a ventilator no," Gove told LBC radio. "The Prime Minister has received some oxygen support and he is kept under, of course, close supervision."
Gove admitted Johnson's intensive care battle was "truly frightening" and said ministers were "praying" for his swift recovery.
Johnson was moved to ICU at St Thomas' Hospital in central London and given oxygen after his health deteriorated sharply over just two hours, leaving doctors fearing he will need a ventilator.
The 55-year-old was transferred to intensive care at 6am (NZT) yesterday because of breathing difficulties - forcing him to "deputise" Raab to take the reins of government.
In a round of broadcast interviews in the UK, Gove said Johnson was getting the "best care".
"As we speak the PM is in intensive care being looked after by his medical team receiving the very, very best care from the team in St Thomas' and our hopes and prayers are with him and with his family," he told BBC Breakfast.
He said Johnson's plight should demonstrate the need to follow social distancing rules, as the virus "has a malevolence that is truly frightening".
Gove played down concerns that the Government will be paralysed with the leader out of action, insisting that Johnson had already been on a "stripped back diary" for days and "Cabinet is the supreme decision-making body".
However, Gove dodged questions about whether Raab has been given crucial national security responsibilities such as control of the nuclear launch codes and military authority.
The Queen is being kept informed about Johnson's condition, while Raab is chairing a meeting of the government coronavirus task force this morning.
Meanwhile, US President Donald Trump revealed he has offered to send Johnson experimental drugs to treat his coronavirus.
"I've asked two of the leading companies ... They've come with the solutions and just have done incredible jobs – and I've asked him to contact London immediately," Trump said.
"The London office has whatever they need. We'll see if we can be of help. We've contacted all of Boris' doctors, and we'll see what is going to take place, but they are ready to go."
The PM's sharp downturn came 11 days after he first suffered coronavirus symptoms and went into isolation. He looked increasingly unwell when glimpsed in public and in "selfie" videos posted on social media, and ministers were then shocked by his grim appearance at a Zoom conference on Sunday.
Downing Street sources confirmed Johnson is not yet on a ventilator - but was moved to intensive care to be near one if needed. Some medical experts forecasting this course of action is now "very likely".
Two thirds of patients in intensive care with coronavirus are sedated and put on a ventilator within 24 hours of arriving as the illness attacks their lungs.
But last night one doctor told The Times Johnson was conscious and had not been intubated - the process of putting a tube in the windpipe to aid breathing. He was said to have required around four litres of oxygen rather than the 15 litres used by an average Covid-19 ICU patient.
Only two hours before his move to intensive care, No 10 was insisting Johnson was still spearheading the government's coronavirus response, despite de facto deputy Raab chairing the morning crisis meeting.
Yet shortly after the Foreign Secretary left the Number 10 podium following the daily 5pm press briefing, Johnson, 55, suffered breathing problems.
Sir Mark Sedwill, the Cabinet secretary, held an emergency video conference with the Cabinet to tell them the bad news, in a moment one minister described as "truly shocking".
No 10 has been urged to be more "transparent" about the premier's condition, amid claims a hospital bed was being prepared for him as early as last Thursday.
In Britain, a further 439 coronavirus deaths were announced yesterday, taking the toll to 5373, while the number of patients rose by 3802 to 51,608.