Celebrities who are "fanning the flames" of conspiracy theories linking 5G technology with coronavirus should be ashamed, a NHS scientist has said.
Videos purportedly showing masts on fire were posted on social media after theories about the link between the mobile technology and Covid-19 circulated online.
Cheers actor Woody Harrelson and former Dancing on Ice judge Jason Gardiner are among stars who have shared theories.
Scientists, however, have completely rejected the claims.
Condemning the theories as "the worst kind of fake news" at Saturday's Downing Street press conference, national medical director of NHS England Professor Steve Powis said: "I'm absolutely outraged, absolutely disgusted, that people would be taking action against the very infrastructure that we need to respond to this health emergency.
"It is absolute and utter rubbish."
Cabinet Secretary Michael Gove added: "That's just nonsense, dangerous nonsense as well."
Dr Michael Head, senior research fellow in global health at the University of Southampton, said: "Conspiracy theorists are a public health danger who once read a Facebook page.
"Here, we also see similar groups of people keen to show their ignorance on a topic where they have no helpful expertise, nor any inclination to post useful public health messages.
"The celebrities fanning the flames of these conspiracy theorists should be ashamed."
Hunger Games actor Harrelson shared an article about the role of 5G in the coronavirus outbreak on his Instagram profile with the caption: "A lot of my friends have been talking about the negative effects of 5G.
"My friend Camilla sent this to me today and though I haven't fully vetted it I find it very interesting."
Ex on the Beach star Calum Best shared a picture with the words "I say no to 5G" on Instagram, along with a YouTube link to a lecture about the virus.
Gardiner, who left Dancing on Ice last year, posted a video called The Threat of 5G on Twitter and wrote: "Doctors and @WHO ask Governments to halt roll out of 5G. Here's why!!"
Meanwhile, Blue singer Lee Ryan urged Instagram followers to believe "truth will prevail without violence".
Alongside a picture of a phone mast on fire, he wrote: "Guys I have to say this!!! Do not start burning up 5g towers!!!!!!!! This is not the way to stand up against it."
Mobile UK, the trade body which represents network providers, said key workers had been abused and infrastructure threatened as a result of the claims.
On Thursday evening, West Midlands Fire Service said eight firefighters attended an incident involving a 70ft tower on a telecommunications site in the Sparkhill area of Birmingham, although the cause of the fire was not determined.
And fire crews were called to a blaze at a phone mast in Aintree, Merseyside, on Friday night but a spokeswoman for Merseyside Fire and Rescue Service said there were "no signs of foul play" so an investigation into its cause was not launched.
The mast had been featured in a video shared on social media the previous weekend by someone who claimed to be measuring radiation from it.
Professor Adam Finn, professor of paediatrics at the University of Bristol, said: "The internet connections these networks give us are one of the most important tools we are using to co-ordinate our response to the epidemic and efforts to do research to overcome it."
Prof Brendan Wren, professor of microbial pathogenesis, at the London School of Hygiene and Tropical Medicine, said a connection between the phone masts and the virus would be "both a physical and biological impossibility".
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