Britain’s media, schools and police forces were told on Thursday to stop promoting an online hoax about the so-called Momo challenge, amid fears that unjustified warnings about the supposed phenomenon risked doing more harm than good.

The Momo challenge centres on false claims that a mysterious character is using WhatsApp messages to encourage children to kill themselves. After it moved from the fringes of the internet to the mass media, interventions from authority figures were blamed for creating a full-blown moral panic – and genuine fear among children.

Questions were raised in parliament on Thursday about what the government planned to do about the hoax, while hundreds of schools sent parents letters warning of the non-existent threat, often featuring technically dubious claims about incitement to violence being spliced into the computer game Fornite or Peppa Pig YouTube videos.

Children’s charities suggested the warnings about the supposed threat posed by the Momo challenge, which is represented by an image of a Japanese puppet with bulging eyes, were “fake news” spread by adults. They said the warnings could become a self-fulfilling prophecy by encouraging children to seek out harmful material.

“When trying to highlight risks to children, particularly in the online arena, it’s important to step back and assess what the real risk is,” Anne Longfield, the children’s commissioner for England, told the Guardian. “Sometimes, however well-meaning, warning of the dangers of something that you haven’t fully looked into amplifies its impact on children beyond the actual fact.”

Longfield, who has a responsibility to represent the views and interests of children, encouraged parents to talk to their offspring, suggesting they are often more media-savvy than their parents: “We have found children themselves are often, in conversation with adults, good judges of what is a real risk and what is simply perceived by adults as one. For figures in authority, getting it wrong too often can actually weaken their warnings of genuine dangers and risks when they do find them.”

In the House of Commons, Conservative MP Douglas Ross called for an urgent debate on the so-called challenge after being contacted by multiple concerned parents in his Moray constituency. He said the parents had heard that children were being encouraged “to contact a number on WhatsApp which then sends them images and instructions on how to harm themselves and others”.

In response, cabinet minister Andrea Leadsom said the government was “extremely concerned” about the Momo challenge but has yet to find any conclusive evidence that children are at risk.

Ross said it was now up to the media to spread the word that the story is a hoax: “We need to make sure all the facts are out there.”

Although the hoax has circulated around the world since last summer, the current wave of moral panic appears to have hit the UK after one woman posted her concerns about the supposed challenge in a community Facebook group for Westhoughton, a town on the edge of Bolton.

This was then massively amplified by traditional news sources, apparently starting with a single story in the Manchester Evening News on 20 February. Parents then flocked to read about the story, with more than 100 stories about the hoax craze published during the last week on the websites of just four national news websites – MailOnline, Daily Star, Daily Express and Daily Mirror, attracting millions of clicks in the process.

Hundreds more stories have been published by local news websites, often reporting on warnings put out by schools, which have been based on no solid information.

The story was given a major boost in the UK when the BBC published a story on its website, sourced to a Facebook post by a police officer based in Craigavon, County Armagh. This included technically unfounded claims that the picture of the Momo challenge doll “is being used by hackers to harvest information” which then “encourages them to add a contact on messaging service WhatsApp, then hounds them with violent images and dares”.

On Thursday BBC wiped the entire article and replaced it with a new piece describing the entire Momo challenge claim as a hoax. The Daily Mirror has retracted a false claim that 130 teenagers in Russia had killed themselves as a result of the supposed craze.

Much of the panic has its roots in legitimate concerns about online child safety, which has been exacerbated by private-sector companies that provide online safety training to schools and police forces issuing public warnings about the supposed threat which are laced with technical errors.

The Police Service of Northern Ireland had claimed that the Momo challenge “conceals itself within other harmless-looking games or videos played by children, and when downloaded it asks the user to communicate with ‘Momo’ via popular messaging applications such as WhatsApp”. There is no evidence to support these claims.

The popularity of the fake story in the UK appears to have resulted in it spreading back to the US, attracting the attention of celebrities such as Kim Kardashian, who have issued public warnings, spreading panic even further.

Ben Rankin, editor of the Mirror online, defended the publication’s coverage as justified because “a huge number of our readers are very concerned” and said that the Mirror had included “sources arguing that it may be overblown”.

“We agree with the National Online Safety Organisation’s stance on this, which is that parents deserve to be armed with the information they need to safeguard their children,” he added.

A BBC spokesperson said that its coverage was prompted by “safeguarding warnings” and had “subsequently been updated to reflect that fact-checkers now say aspects of the ‘Momo’ story is a hoax”.