US President Donald Trump revealed he is taking hydroxychloroquine, a malaria drug that he has touted despite medical warnings about its use, as a preventative medicine against the coronavirus. 

"I've been taking it for the last week-and-a-half. A pill every day," Mr Trump told reporters. 

Mr Trump made the disclosure during a question-and-answer session with reporters during a meeting with restaurant executives about the impact of the virus.

Weeks ago, Mr Trump had promoted the drug as a potential treatment for the virus but subsequent studies found that it was not helpful. 

Mr Trump, 73, who is tested daily for the virus, said he had asked the White House physician if it was okay to take the drug, and the doctor told him, "well, if you'd like it".

The disclosure came as Moderna Inc reported progress in a potential vaccine for the virus.

The only drug that has emerged as a potential treatment is Gilead Sciences Inc's remdesivir, a drug reserved for hospital patients.

Meanwhile, Mr Trump attacked the United Nations health body as a Chinese "puppet" and confirmed he is considering slashing or canceling US support. 

"They're a puppet of China, they're China-centric to put it nicer," he said at the White House. 

Mr Trump said the United States pays around $450 million annually to the World Health Organization, the largest contribution of any country. Plans are being crafted to slash this because "we're not treated right".

"They gave us a lot of bad advice," he said of the WHO. 

Mr Trump spoke as the WHO held its first annual assembly since the pandemic swept the world after originating in China, causing massive economic disruption and killing 316,000 people - close to a third of them in the United States.

Mr Trump said China only pays about $40 million a year and one idea was for Washington to bring "our 450 down to 40," but "some people thought that was too much".