Boris Johnson's spokesman denies reports by the Russian state media that the prime minister is being treated in hospital with a ventilator.

Johnson was admitted to hospital on Sunday after continuing to experience a high temperature and cough, ten days after testing positive for the coronavirus.

His spokesman said he would remain in hospital under observation, but insisted he was "comfortable."

He refused to deny separate reports that Johnson has received oxygen treatment.

However, he labelled Russian reports that he is on a ventilator as "disinformation."

Downing Street also refused to confirm or deny whether the prime minister is suffering from pneumonia.

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The UK government has accused Russia of spreading "disinformation" after the country's state media reported that Prime Minister Boris Johnson was being treated on a ventilator for the coronavirus.

Johnson was admitted to hospital on Sunday after experiencing "persistent symptoms" of the coronavirus.

His spokesman confirmed on Monday that the prime minister was admitted to St Thomas Hospital in London after continuing to experience a high temperature and a cough ten days after first testing positive for the virus.

However, he described Russian state media reports that he is on a ventilator for the condition as "disinformation."

"That is disinformation," his spokesman said.

"Our specialist government units have seen a rise in false reports since the coronavirus outbreak started. It's vital that any information is knocked down quickly."

He added that it was "vital to ensure that we press social media companies for further action to stop the spread of disinformation."

Boris Johnson insists he is 'in good spirits'

Downing Street also repeatedly refused to confirm or deny whether Johnson has pneumonia, but insisted that he had "a comfortable night" and was "in good spirits."

"The prime minister was admitted to hospital for tests last night as a precaution," his spokesman said.

"The issue is that his symptoms have remained persistent. The prime minister had a comfortable night in St Thomas's hospital and is in good spirits. He remains in hospital under observation."

Johnson's official Twitter account also carried a message purportedly from the prime minister.

Last night, on the advice of my doctor, I went into hospital for some routine tests as I'm still experiencing coronavirus symptoms. I'm in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe.

Johnson's spokesperson could not confirm when they expected Johnson to be discharged.

"As soon as there are any details about the PM leaving hospital we will let you know straight away," he said.

They also insisted that Johnson would continue to lead the government from his hospital bed.

"Any information the PM needs to be updated on or any decisions that require action from the PM, that is what will happen," he said.

"He is receiving updates in hospital and continuing to receive a [ministerial] box."