An online “game” that supposedly encourages young people to harm themselves and in some cases even take their own lives has been branded a hoax by children’s charities.

Momo - described as a WhatsApp “suicide challenge” - purportedly features an avatar of a woman with dark hair, pale skin and oversized eyes, who sends young people images and instructions on how to harm themselves and others. But after a series of warnings about the game spread across UK social media this week fact-checkers and charities declared Momo a hoax.

“News coverage of the momo challenge is prompting schools or the police to warn about the supposed risks posed by the momo challenge, which has in turn produced more news stories warning about the challenge,” says The Guardian’s Jim Waterson.

Kate Tremlett, harmful content manager at the UK Safer Internet Centre, also questioned the viral social news story, telling the newspaper: “It’s a myth that is perpetuated into being some kind of reality,” she said.

After a lengthy investigation, the NSPCC said there is no evidence to show the phenomenon is actually posing a threat to British children and added that it has received more phone calls about it from members of the media than concerned parents.

A Samaritans spokesperson was similarly sceptical, telling The Guardian: “These stories being highly publicised and starting a panic means vulnerable people get to know about it and that creates a risk.”

They recommended media outlets read their guidelines on reporting suicide and suggested press coverage is “raising the risk of harm”.

The story began circulating when reports emerged that a girl aged 12 and a boy of 16 killed themselves in northeastern Colombia in September after receiving Momo messages.

Local media at the time reported that the teenage boy knew the girl and passed the game to her before killing himself. She was reportedly found hanged two days later.

Colombian government secretary Janier Landono said: “Apparently, they practised this game through WhatsApp and it invited the young people to hurt themselves. The game has different challenges and the suicide is at the end.”

Reports of the game reached the UK earlier this month when a concerned mother from Bolton wrote on a local Facebook group that her son had been influenced by the game. Her seven-year-old boy “told his school friends that doll-like creatures would kill them in their sleep”, reports the Daily Mail.

She said: “When I collected him from school the teacher asked to talk to me. She said he had made three kids cry by telling them that Momo was going to go into their room at night and kill them.

“When we got home I spoke to him about this and he told me some kids at school had told him to look at the Momo challenge, which he did.”

How was the Momo challenge reported?

“Users who engage with Momo on WhatsApp are sent disturbing and graphic photographs and in some cases are ‘doxed’ into self-harm and suicide,” 9News Australia reported.

Doxing “is when someone hacks your private information and then threatens to share it online or in a public forum, akin to blackmail”, the news site adds.

Fox News claimed Momo was “also linked to the theft of personal data, harassment, extortion, anxiety, depression and insomnia”.

Where did the whole thing originate?

The game was said to have started in Mexico, with players “challenged” to communicate on WhatsApp with an unknown person known as Momo, according to the Computer Crime Investigation Unit of the State of Tabasco, Mexico.

The disturbing avatar was initially believed to show a work by Japanese artist Midori Hayashi, but is actually of a sculpture created by Japanese special effects company Link Factory and displayed at a Tokyo gallery.

Neither the company nor Hayashi had anything to do with the hoax, which began being shared online in August 2016, says The Independent.

According to Fox News, the Momo icon has begun appearing as an avatar or so-called mod in the popular video game Grand Theft Auto 5, while Momo content has also been added to the popular children's game Minecraft, owned by Microsoft.

Childline in the UK can be reached on 0800 1111, or by confidential email via its website.

Anyone experiencing suicidal thoughts can call the Samaritans free on 116 123 or contact them online for confidential, 24-hour support.