The conspiracy theory connecting the coronavirus outbreak to the roll-out of the 5G network is the most common piece of fake news about the virus seen by people in the UK, new research shows.

The proportion of British adults who have viewed misinformation about the pandemic has increased from 46 per cent to 50 per cent, according to Ofcom’s latest findings.

And 50 per cent of the population said they had come across “theories linking the origins or causes of Covid-19 to 5G technology”.

The watchdog’s latest report on information consumption during the crisis — covering week three of the lockdown — paints a worrying picture of how widespread the utterly discredited conspiracy has become.

False narratives around 5G and the virus have been shared hundreds of thousands of times on social media, with photos and videos documenting attacks on mobile phone masts often overlaid with spurious information about Covid-19.

Some 50 fires targeting masts and other equipment have been reported in Britain in recent weeks, leading to three arrests. Telecom engineers have been abused on the job 80 times over the past month, according to trade group Mobile UK.

The UK is not the only country in which the wild and baseless conspiracy theory has taken off. Some 16 masts have been torched in the Netherlands, with attacks also reported in Ireland, Cyprus, and Belgium.

Ofcom said it has issued “guidance” to ITV over “ill-judged” comments made by Eamonn Holmes about the discredited theory. The media watchdog also imposed a sanction on ESTV over a London Live interview with conspiracy theorist David Icke — a believer in reptilian humanoids — about the virus.

“Broadcasters have editorial freedom to discuss and challenge the approach taken by public authorities to a serious public health crisis such as the coronavirus,” said an Ofcom spokeswoman.

“However, discussions of unproven claims must be put fully into context — especially at a time when mobile phone masts in the UK are being attacked, risking significant harm to the public.”

Culture secretary Oliver Dowden met with Facebook, Twitter and Google officials earlier this month to discuss how they could clamp down on disinformation.

The latest Ofcom report shows people said they were most likely to seek information on the pandemic from the BBC, other broadcasters or official sources like the NHS, government or World Health Organisation (WHO).

Social media and closed groups continue to be the least trusted media, with just under a quarter of respondents saying they trusted the information viewed on WhatsApp.

In an encouraging development, the proportion of respondents who say they are “finding it hard to know what’s true and what’s false” about the coronavirus has dropped from 40 per cent in week one of the lockdown to 32 per cent in week three.

Meanwhile the proportion of respondents using a fact-checking site has increased since the lockdown began, from 10 per cent to 15 per cent.