The United States' closest international ally is in a state of incredulity and "disbelief" at how badly President Donald Trump has handled the coronavirus outbreak.

UK government officials said the president's slow response and his tweets seeking to downplay the spread of the virus have triggered disbelief among Prime Minister Boris Johnson's administration.

One UK official accused Trump of spreading misinformation about COVID-19, the illness caused by the virus.

Trump and Johnson's relationship has deteriorated in recent months — last month, the president hung up the phone on the prime minister in a moment of "apoplectic" fury.

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The UK government is in "genuine disbelief" about how badly US President Donald Trump has handled the coronavirus outbreak, with officials reacting with "incredulity" to the president's attempts to downplay the epidemic.

The Trump administration's slow response and the president's stream of tweets about COVID-19, the disease caused by the virus, have been received badly by Prime Minister Boris Johnson's team, UK officials told BuzzFeed News.

"There is a general level of incredulity over his comments but especially over the lack of testing," a UK official told the website.

People in the UK government "are used to the steady stream of tweets, but the last few days have caused more than the usual eye-rolling," the official said. "There is genuine disbelief."

In the past week, the president has used the outbreak to attack his Democratic opponents.

The president has labeled the outbreak a "hoax" and falsely claimed that "anyone who wants a test can get a test."

He also reportedly has become fixated on keeping the official number of US cases low.

Referring to Trump's response and a new UK government unit designed to counter misinformation about the virus online, a UK official told BuzzFeed News that "our COVID-19 counter-disinformation unit would need twice the manpower if we included him in our monitoring."

Johnson has distanced himself from Trump after an 'apoplectic' call

Trump and Boris Johnson. Getty

Trump and Johnson's relationship has deteriorated in recent months as Johnson has sought to distance himself from the president.

The two men have had a series of public disagreements on everything from telecoms policy to trade to the president's conflict with Iran.

Last month, the president hung up the phone on Johnson in a moment of "apoplectic" rage, after which he accused the prime minister of "betrayal."

Johnson subsequently canceled his trip to the White House that was set to take place later in March.