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President Donald Trump said Friday that his remarks on injecting disinfectants to treat COVID-19 were sarcasm, after doctors responded with horror and disinfectant manufacturers urged people not to ingest the poisonous substances.

"I was asking a question sarcastically to reporters just like you, just to see what would happen," Trump said on Friday during a bill signing for the coronavirus aid package. "I was asking a sarcastic and a very sarcastic question to the reporters in the room about disinfectant on the inside. But it does kill it and it would kill it on the hands, and it would make things much better."

But the president's comments the day before — a lengthy musing that disinfectant or powerful light could be used to fight the virus — did not appear to be sarcasm; they were in part directed at a Homeland Security official.

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Ingesting or injecting bleach into the body is extremely dangerous and doctors immediately called the president's suggestion "irresponsible" and "dangerous."

Trump denied he was asking his experts to investigate the issue, and repeatedly reiterated that disinfectant on the hands and sun can damage or kill the coronavirus. He said he was urging his officials to investigate how "sun can help us."

Here's what the president said in Thursday night's briefing:

"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. Because you see it gets in the lungs and it does a tremendous number on the lungs. So it would be interesting to check that. So, that, you’re going to have to use medical doctors with. But it sounds, it sounds interesting to me.”

He also asked Dr. Deborah Birx, the White House pandemic response coordinator, to ask doctors whether heat and light could be used to treat the virus.

"Not as a treatment," she said. "Certainly fever is a good thing, when you have a fever, it helps your body respond. But I have not seen heat or light…"

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

Pressed by a reporter on Thursday on offering "rumors" to the American people, Trump said, "I'm the president and you're fake news."