Marc Owen Jones, a researcher at Hamad bin Khalifa University in Qatar, who specializes in online disinformation networks, analyzed 22,000 recent interactions on Twitter mentioning “5G” and “corona,” and said he found a large number of accounts displaying what he termed “inauthentic activity.” He said the effort bears some hallmarks of a state-backed campaign.

“There are very strong indications that some of these accounts are a disinformation operation,” Jones said.

Jones said the campaign uses a strategy similar to Russia’s Internet Research Agency, which was behind a disinformation campaign during the 2016 U.S. presidential campaign. But he said he hasn’t yet concluded that Russia, or any other government or organization, is behind the effort.

Blackbird.AI, a New York-based company that monitors online disinformation campaigns, said it had in recent weeks identified a surge in the number of social media posts promoting the 5G conspiracy theory. In the previous 24 hours, there had been more than 50,000 posts about the topic on Twitter and Reddit, Naushad UzZaman, the company’s chief technology officer and co-founder, said on Wednesday.

There has been a “significant uptick in inauthentic amplification” of posts on social media linking 5G to the coronavirus, UzZaman said, indicating that there could be a coordinated campaign and bot accounts involved. The company says it uses a system that analyzes language, communication patterns, post volumes and bot activity in order to identify social media posts that are “inauthentic” and attempting to manipulate online discussion.

Blackbird.AI hasn’t determined who is behind the effort, nor have the researchers at the Global Disinformation Index, a non-profit that tracks disinformation online. “We’ve definitely seen plenty of organized disinfo around 5G-coronavirus,” said Danny Rogers, the index’s co-founder.

False stories on social media can be disseminated broadly by both government and non-government groups — with bot accounts available for purchase or rental online, said Lee Foster, a senior manager at the cybersecurity firm FireEye Inc. “The barriers to entry are really low, so any number of actors can replicate the same kind of techniques.”

Twitter declined to comment. A Reddit spokesperson said the company was focused on “connecting people with authoritative content and experts” and has dedicated teams that “detect and mitigate attempts at manipulating content.”

Conspiracy theories about health risks associated with 5G have circulated since at least 2016. They were first spread on internet forums and YouTube, and were later picked up by the website InfoWars and Russian state broadcaster RT, which published stories cautioning that 5G could be “a global catastrophe,” causing cancer in humans and wildlife.

Earlier this year, as Covid-19, the disease caused by the coronavirus, began to spread from China to the rest of the world, fringe groups began claiming that the virus was linked to 5G technology. The claims may have originated with comments made by a doctor in Belgium, saying he believed 5G was “life-threatening” and connected to the coronavirus, while noting that he had “not done a fact-check,” according to an article in Wired magazine. The newspaper that printed his comments retracted the story, but that didn’t stop the conspiracy theory from gaining traction.

Some celebrities — including the singer M.I.A. and the actor John Cusack — have fanned the flames, posting suggestions on social media that 5G is linked to the spread of the virus or otherwise poses health risks. Meanwhile, users of online forums such as 4chan have encouraged people to vandalize 5G equipment.

In recent days, at least 20 mobile phone masts have been attacked in the U.K., some set on fire, and British telecommunications companies have issued statements saying the 5G conspiracy theory has led to abuse of their employees. Some users of 4chan celebrated the news that 5G mobile phone masts had been targeted by arsonists and encouraged copycat actions.

There is no scientific basis for the concerns, according to Simon Clarke, associate professor in cellular microbiology at the University of Reading. “The idea that Covid-19 is caused by 5G mobile phone signals is complete rubbish,” said Clarke. “5G radio signals are electromagnetic waves, very similar to those already used by mobile phones. Electromagnetic waves are one thing, viruses are another, and you can’t get a virus off a phone mast.”

Some social media companies have taken action to limit the spread of coronavirus conspiracy theories on their platforms. On Tuesday, Google’s YouTube said that it would ban all videos linking 5G technology to coronavirus, saying that “any content that disputes the existence or transmission of Covid-19” would now be in violation of YouTube policies.

In the U.K., a parliamentary committee on Monday called on the British government to do more to “stamp out” coronavirus conspiracy theories, and said it was planning to hold a hearing later this year at which representatives from U.S. technology giants will be asked about how they have handled the spread of disinformation on their platforms.

“If they don’t sort situations like this quickly, they are going to end up with a worldwide regulatory regime,” Julian Knight, a conservative member of parliament who heads the Digital, Culture, Media and Sport Committee, said in an interview. “They have a duty of care to wider society, they have skin in the game — particularly during a viral outbreak, which can affect anyone at any time.”

More must-read tech coverage from Fortune:

—A medical giant is sharing its ventilator designs. Will that change anything?
—New IBM CEO Arvind Krishna: “We will hit a new normal sometime this year”
—Questions mount over Apple’s next iPhone models, DarkSky acquisition, and “anti-competitive behaviors”
—The top pharmaceutical inventors and innovators
—Listen to Leadership Next, a Fortune podcast examining the evolving role of CEO
—WATCH: Best earbuds in 2020: Apple AirPods Pro Vs. Sony WF-1000XM3

Catch up with Data Sheet, Fortune’s daily digest on the business of tech.