LONDON — On April 2, a wireless tower was set ablaze in Birmingham. The next day, a fire was reported at 10 p.m. at a telecommunications box in Liverpool. An hour later, an emergency call came in about another cell tower in Liverpool that was going up in flames.

Across Britain, more than 30 acts of arson and vandalism have taken place against wireless towers and other telecom gear this month, according to police reports and a telecom trade group. In roughly 80 other incidents in the country, telecom technicians have been harassed on the job.

The attacks were fueled by the same cause, government officials said: an internet conspiracy theory that links the spread of the coronavirus to an ultrafast wireless technology known as 5G. Under the false idea, which has gained momentum in Facebook groups, WhatsApp messages and YouTube videos, radio waves sent by 5G technology are causing small changes to people’s bodies that make them succumb to the virus.

The incidents starkly demonstrate how coronavirus conspiracy theories have taken a dark turn by spilling out into the real world. In just a few weeks, the pandemic has given pre-existing fringe ideas online new urgency by playing on people’s fears.