Donald Trump’s widely-criticised admission that he is taking a malaria drug to try to protect against coronavirus “should be ignored”, a former chief scientific adviser has urged.

Sir David King said the US President is “making it up as he goes along” after Mr Trump said he is using hydroxychloroquine, despite there being no evidence it combats Covid-19.

Mr Trump’s own government warns that the drug should only be administered for coronavirus in a hospital or research environment because it has potentially fatal side effects.

Work and Pensions Secretary Therese Coffey said on Tuesday that the admission was surprising but declined to label the admission irresponsible.

But Sir David, a Cambridge University professor who advised the UK Government under both Tony Blair and Gordon Brown, was clear on what he thought of Mr Trump’s approach to science.

“I think he speaks from the top of his head and every word he says should be ignored in terms of advice,” Sir David told ITV’s Good Morning Britain.

“I’m sorry but this is not the pronouncements of a person who is listening to the scientists. He is making it up as he goes along.”

Sir David King
Sir David King advised the UK Government under Tony Blair and Gordon Brown(Jonathan Brady/PA)

Criticism was mounting against the president but Ms Coffey said it was a matter “which I do not want to comment on” when asked if it was irresponsible.

“I think it surprised a lot of people last night when President Trump announced this,” she told BBC Breakfast.

“However, that really is a matter between him and his clinician rather than the Government of the UK.”

But Downing Street stressed that taking hydroxychloroquine to ward off coronavirus was “not something we recommend doing”.

The Prime Minister’s official spokesman said: “It’s not something which our own medical experts are recommending.”

Asked whether Mr Trump was setting a bad example, the spokesman said: “I can only set out what the UK’s advice is. It’s not something that we recommend doing.”

Mr Trump, who previously was widely criticised and ridiculed for suggesting disinfectant could be injected into the body to treat coronavirus, made his latest shock statement after some in the White House tested positive for Covid-19.

Despite saying he has had “zero symptoms”, he told reporters he had been taking hydroxychloroquine “for about a week-and-a-half now” after requesting it from a White House doctor.

“I started taking it, because I think it’s good,” the 73-year-old president said. “I’ve heard a lot of good stories.”

However, the US Food and Drug Administration last month warned health professionals that regulators had received reports of heart rhythm problems, including deaths.

Mr Trump went on to threaten to permanently withhold funding from the World Health Organisation as he continued his criticism of the group with the US suffering the highest Covid-19 death toll.