Authorities in the UK are probing a series of fires involving mobile phone towers amid concerns the sites may have been targeted because of conspiracy theories linking COVID-19 to the 5G network.

Three fires at mobile phone towers had recently been reported in Birmingham, Liverpool and Melling in Merseyside, the BBC reports.

On Friday, emergency services were called to reports that a 5G mast was on fire in Liverpool, according to The Guardian.

Liverpool mayor Joe Anderson told The Guardian he had received threats relating to the conspiracy theories linking COVID-19 to 5G technology, which were spreading on social media.

"The suggestion that COVID-19 is somehow linked to 5G is patently beyond the realms of credibility – utterly bizarre," he said.

"In Liverpool these masts are being upgraded and ironically the very people that are using this technology are the ones who are believing these theories. I was mildly threatened yesterday by someone telling me to take them down."

Three mobile phone towers in the Uk have been set alight amid conspiracy theories linking the new technology to COVID-19. (Getty)

Several celebrities have helped to fan the flames of the conspiracy theories on social media, with Cheers actor Woody Harrelson, former Dancing on Ice judge Jason Gardiner and Amanda Holden, a judge on Britain's Got Talent, all posting about the topic online, the newspaper said.

The Department for Digital, Culture, Media and Sport took to Twitter to debunk the theories, saying "there is absolutely no credible evidence" of a link.

Cabinet secretary Michael Gove told reporters yesterday the theories were "dangerous nonsense".

Meanwhile, National Medical Director of NHS England, Professor Steve Powis, condemned them as "the worst kind of fake news".

"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," he said.