Facebook has stepped up efforts to stop the promotion of baseless conspiracy theories linking Covid-19 to 5G, after research highlighted a “toxic cocktail” of far-right-influenced groups pushing the idea alongside incitement to attack telecommunications infrastructure.

Groups in the UK promoting the conspiracy theory on Facebook – often linking it to explicitly antisemitic messages – have been growing at a significant rate, warned the campaign group Hope not Hate.

The largest group in the UK, Stop 5G UK, added almost 3,000 members in just 24 hours from 6-7 April while another, Direct Action Against 5G, gained more than 1,400 members in its first week after it was created on 31 March.

Hope not Hate warned that an ever-growing number of Facebook users are now accessing posts that not only encourages them to take illegal action against 5G infrastructure but also contains potentially damaging misinformation about health and wellbeing.

Almost a third of British people say they can’t rule out a link between coronavirus and 5G, according to new polling revealing the extent of the baseless conspiracy theory.

Some 8% believe there is a link, while 19% are unsure, according to the survey of 2,032 adults by the polling firm Focaldata.

At least 20 phone masts across the UK are believed to have been set alight or otherwise vandalised since the start of the coronavirus crisis, according to government and industry sources who said this month that they have grown increasingly concerned about the impact of the baseless claims about risks associated with the next-generation mobile technology.

An analysis by Hope not Hate researchers of recent posts from six UK-based anti-5G Facebook groups has found evidence of a “toxic cocktail” of influence from far-right activists and others, where antisemitic and anti-government conspiracies are combined with calls to illegal direct action.

Stop 5G UK has people posting pictures of masts in their area of west London and asking what they were, before being urged by other users to “burn it” and “drive into it”.

The wiring of a telecoms mast damaged by fire in Sparkhill, Birmingham. Photograph: Carl Recine/Reuters

A post which combined antisemitic tropes and conspiracy theories about 9/11 received more than a hundred likes and was shared dozens of times.

On another group, a user who posted pictures of masts in his town was urged by others to “burn it” and “bomb them before it bombs us”.

Facebook told the Guardian that it had removed the Stop 5G UK group following violations of its “promoting or publicising” crime policies before it received the report from Hate not Hate and has since removed a Destroy 5G Save Our Children group. It also removed a number of other posts flagged by Hope not Hate.

It said it had begun removing false claims that 5G technology causes Covid-19: “We are taking aggressive steps to stop misinformation and harmful content from spreading on our platforms and connect people to accurate information from the NHS about coronavirus. Content encouraging attacks on 5G masts clearly violates our policies and we have removed a number of pages, groups and posts.”

Facebook added: “Over the last week, under our existing policies against harmful misinformation, we have also begun removing false claims that 5G technology causes the symptoms of or contraction of Covid-19.”