US President Donald Trump has been lambasted by the medical community after suggesting research into whether coronavirus might be treated by injecting disinfectant into the body.

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He also appeared to propose irradiating patients' bodies with UV light, an idea dismissed by a doctor at the briefing.

Another of his officials had moments earlier said sunlight and disinfectant were known to kill the infection.

Trump's own public health agencies warn against bleach as a medicine.

During Thursday's (Friday NZT) White House coronavirus task force briefing, an official presented the results of US government research that indicated coronavirus appeared to weaken more quickly when exposed to sunlight and heat.

The study also showed bleach could kill the virus in saliva or respiratory fluids within five minutes and isopropyl alcohol could kill it even more quickly.

William Bryan, acting head of the US Department of Homeland Security's Science and Technology Directorate, outlined the findings at the news conference.

While noting the research should be treated with caution, Trump suggested further research in that area.

"So, supposing we hit the body with a tremendous - whether it's ultraviolet or just very powerful light," the president said, turning to Dr Deborah Birx, the White House coronavirus response co-ordinator, "and I think you said that hasn't been checked but you're going to test it.

"And then I said, supposing you brought the light inside of the body, which you can do either through the skin or in some other way. And I think you said you're going to test that too. Sounds interesting," the president continued.

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"And then I see the disinfectant where it knocks it out in a minute. One minute. And is there a way we can do something like that, by injection inside or almost a cleaning?

"So it'd be interesting to check that."

Pointing to his head, Trump went on: "I'm not a doctor. But I'm, like, a person that has a good you-know-what."

He turned again to Dr Birx and asked if she had ever heard of using "the heat and the light" to treat coronavirus.

"Not as a treatment," Dr Birx said. "I mean, certainly, fever is a good thing, when you have a fever it helps your body respond. But I've not seen heat or light."

"I think it's a great thing to look at," Trump said.

A journalist at the briefing questioned whether Trump's off-the-cuff remarks could spread dangerous disinformation to Americans.

Doctors warned the president's idea could have fatal results.

Pulmonologist Dr Vin Gupta told NBC News: "This notion of injecting or ingesting any type of cleansing product into the body is irresponsible and it's dangerous.

"It's a common method that people utilise when they want to kill themselves."

Kashif Mahmood, a doctor in Charleston, West Virginia, tweeted: "As a physician, I can't recommend injecting disinfectant into the lungs or using UV radiation inside the body to treat Covid-19.

"Don't take medical advice from Trump."

John Balmes, a pulmonologist at Zuckerberg San Francisco General Hospital, warned that even breathing fumes from bleach could cause severe health problems.

He told Bloomberg News: "Inhaling chlorine bleach would be absolutely the worst thing for the lungs. The airway and lungs are not made to be exposed to even an aerosol of disinfectant.

"Not even a low dilution of bleach or isopropyl alcohol is safe. It's a totally ridiculous concept."

Trump has previously hyped a malaria medication, hydroxycloroquine, as a possible treatment for coronavirus, though he has stopped touting that drug recently.

This week a study of coronavirus patients in a US government-run hospital for military veterans found more deaths among those treated with hydroxychloroquine than those treated with standard care.

Reacting to the president's remarks on Thursday evening, Joe Biden, his likely Democratic challenger in November's White House election, tweeted: "UV light? Injecting disinfectant? Here's an idea, Mr President: more tests. Now. And protective equipment for actual medical professionals."