At least 20 mobile phone masts across the UK are believed to have been torched or otherwise vandalised since Thursday, according to government and industry sources who are increasingly concerned about the impact of baseless theories linking coronavirus to 5G networks.

There have been noticeable clusters of attacks on masts around Liverpool and the West Midlands. Owing to the slow rollout of 5G in the UK, many of the masts that have been vandalised did not contain the technology and the attacks merely damaged 3G and 4G equipment.

There is hope that the rate of attacks may now be slowing. Network operators are particularly concerned about the safety of their staff, as members of the public have confronted telecoms engineers maintaining critical infrastructure, sometimes filming the encounters to share on social media. Mobile operators and home broadband providers estimate there have been at least 30 such incidents in the last week.

Engineers for O2 have been issued with signs to display in their vans while working. The signs, which read “Key worker, keeping your network running”, are intended to spread the message that communications workers are playing a crucial role during the current crisis.

Social networks will meet the government in the coming days to explain what they can do to stop the spread of baseless claims about 5G, although there is a limited amount that can be done to stop videos and messages spreading on messaging services such as WhatsApp.

Despite repeated assurances from international radiation watchdogs that 5G is safe, baseless theories about its purported risks have long bubbled away at the fringes of the internet – in common with previous generations of the telecoms technology. However, the rapid explosion over the last week of claims linking the new telephone standard to the pandemic – fanned by some celebrities and influencers – has caught the industry and the government off guard.

While many long-running Facebook groups have opposed the rollout of 5G technology, in the last week the social network has had to delete multiple pages encouraging vandalism of the phone network. The number of attacks rose rapidly following a suspected arson attack on a mast in Birmingham on Thursday night. Vodafone confirmed that six sites were targeted over the weekend, and other networks suggested they had seen similar numbers.

MobileUK, the industry group that unites the UK’s four main mobile networks, published an open letter to customers asking for help to stop the vandalism.

“We have experienced cases of vandals setting fire to mobile masts, disrupting critical infrastructure and spreading false information suggesting a connection between 5G and the Covid-19 pandemic,” the open letter says. “There is no scientific evidence of any link between 5G and coronavirus. Fact.

“Please help us to make this stop. If you witness abuse of our key workers please report it. If you see misinformation, please call it out. Your help will make a real difference.”