Singer Annie Lennox has blasted Madonna for a social media post promoting coronavirus conspiracy theories and a fake cure for the deadly virus.

On Tuesday, Madonna shared a video of false claims on Instagram that had previously been supported by US President Donald Trump, suggesting the drug hydroxychloroquine is potential cure for COVID-19.

In the post, Madonna described controversial US doctor Stella Immanuel – who appears in the video – as her “hero”.

“The truth will set us all free!” she wrote. “But some people don’t want to hear the truth. Especially the people in power who stand to make money from this long drawn-out search for a vaccine. Which has been proven and has been available for months. They would rather let fear control them and let the rich get richer and the poor and sick get sicker.”

The post was quickly blurred by Instagram, which said it contained “false information”. By Wednesday morning (US time), it had been taken down.

But not before it had been spotted by Lennox, one half of the 1980s duo The Eurythmics. She was one of the first to blast the claims, calling it “dangerous quackery”.

“This is utter madness!!! I can’t believe that you are endorsing this dangerous quackery. Hopefully your site has been hacked and you’re just about to explain it…” she wrote in response.

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Instagram has fact-checked content and flagged inaccuracies since late in 2019.

“We’ve removed this video for making false claims about cures and prevention methods for COVID-19,” Instagram policy communications manager Raki Wane said of Madonna’s post.

“People who reacted to, commented on, or shared this video, will see messages directing them to authoritative information about the virus.”

Dr Immanuel has been in the spotlight after appearing among a group of lab coat-wearing doctors who posted an online video on Monday (local time) with a string of inaccurate claims about COVID that contradicted official US government guidelines.

“You don’t need masks. There is a cure,” Dr Immanuel said.

The doctor has also previously shared conspiracy theories about alien DNA and “demon sperm”.

Earlier this week, Mr Trump tweeted a version of the video, which rapidly gained tens of thousands of views on Facebook and YouTube before both companies took it down. The President’s son, Donald Trump Jr, had his Twitter account restricted by the company for 12 hours after calling the video a “must-watch”.

On Tuesday, Mr Trump stormed out of a White House briefing after being questioned about the video and the doctor’s claims.

Mr Trump has repeatedly endorsed hydroxychloroquine as a potential cure for the coronavirus, and even admitted to taking it himself. But the World Health Organisation maintains there is no proof that the drug cures the virus, and its misuse could cause “serious side effects and illness, and even lead to death”.

Madonna as seen in her now-deleted bathtub video. Photo: Instagram

Earlier in the COVID pandemic, Madonna caused another stir by posting a video of herself sharing commentary on the deadly virus from her bathtub.

Madonna declared that the virus was a “great equaliser” that has rendered people “equal in many ways”, without regard to age, wealth or social status.

That post has also since been removed.