U.K. Prime Minister Boris Johnson is in hospital | Pippa Fowles/EPA Reports Boris Johnson is on a ventilator are ‘Russian disinformation’ UK prime minister remains under observation at a London hospital but is ‘in good spirits,’ spokesman said.

LONDON — The British government on Monday dismissed a Russian media report that the U.K. prime minister had been put on a ventilator after being hospitalized with persistent coronavirus symptoms.

Boris Johnson, who said he tested positive for COVID-19 on March 27, was admitted to hospital on Sunday for tests. On Monday, Russia's news agency RIA Novosti quoted an unnamed healthcare source saying that Johnson had been given "artificial ventilation of his lungs."

The prime minister's spokesman dismissed the report as "disinformation."

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

The Department for Digital, Culture, Media and Sport and the Cabinet Office "continue to work closely with social media companies to stop the spread of false information and rumors," he added.

Johnson remains under observation at St. Thomas' Hospital in London with a persistent temperature and cough, but had a "comfortable night" and "is in good spirits," the spokesman said, adding Johnson is still in charge of government and continues to receive updates as well as his red box containing government papers.

However, the spokesman declined to provide any further details on whether the prime minister is receiving any treatment or whether he is intensive care.