A Lancashire school has warned parents that a sick online game is hacking into Peppa Pig clips on YouTube.

It comes after a concerned mum in Westhoughton warned about the game, known as the MOMO challenge, which is played via social media platforms including WhatsApp, Facebook and YouTube.

The disturbing game encourages children to hurt themselves after they have been invited to take part by an anonymous controller.

YouTube said it had not received any evidence of the challenge on its site.

In a post on Facebook, Haslingden Primary School in Rossendale, East Lancashire, warned seemingly innocent videos were being circulated on YouTube which showed a normal, child-friendly clip, with MOMO added in.

The post read: "We have become increasingly aware of highly inappropriate videos circulating online and are being viewed by children across the school.

"These video clips are appearing on many social media sites and YouTube (including Kids YouTube).

"One of the videos starts innocently, like the start of a Peppa Pig episode for example, but quickly turn into an altered version with violence and offensive language.

"Another video clip is going by the name of 'MoMo' which shows a warped white mask which is promoting children to do dangerous tasks without telling their parents.

"Examples we have noticed in school include asking the children to turn the gas on or to find and take tablets.

"As you can imagine, this is highly distressing for the children to view. We encourage you to be vigilant when your child is using any device or watching any clips.

"We would also encourage all parents/carers to remind the children of our school online rules:

"KS1: If it upsets you, switch off the screen and tell an adult.

"KS2: Save it, block it, report it.

"If you have any concerns or questions, please speak to your child's class teacher."

Last week a concerned mum from Westhoughton, in Bolton, warned other parents about the game.

The mum, who asked to remain anonymous, said she was “deeply alarmed” after being told by a teacher that someone at the school had made children cry by telling them “Momo was going to go into their room at night and kill them”.

In the post, published on the ‘Love Westhoughton’ Facebook page, she said: “When I collected him from school the teacher asked to talk to me.

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

She added: “When ***** watched a video the Momo character told him to tell everyone to fear Momo or it will kill him in his sleep.

“So I have one very frightened little boy and some deep concerns about the kids in his school.

“Parent controls are as tight as could be and this s*** still slips through.

“So if you have a child it would be well worth it to open up a dialogue about idiots online and try to get ahead of this."

What is Momo?

MOMO is a brown haired young woman with bulging eyes and creepy, bird-like legs. She was originally created by Japanese artist Midori Hiyashi for the Link Factory, none of which have any connection to the horrifying game.

The game apparently hides itself in the form of other normal looking games so that parents do not suspect it. MOMO then asks the player to add a number on WhatsApp, which may also be found on YouTube.

A YouTube spokeswoman said: “Contrary to press reports, we have not received any evidence of videos showing or promoting the Momo challenge on YouTube.

“Content of this kind would be in violation of our policies and removed immediately.”

No links or videos that violate the online giant’s guidelines or promote the Momo challenge have been flagged with YouTube.

How to keep your child safe

To stay safe, parents are warned to always be aware of what their children are watching and reading online, and if possible, limit the apps they can access.

If a parent suspects a MOMO is targeting their child, police advise to delete and block the number immediately.

In Northern Ireland police released a statement warning parents.

Detective Sergeant Elaine McCormill said: "I am disgusted that a so-called game is targeting our young children and I would encourage parents to know what your children are looking at and who they are talking to. Whilst the threat of a curse may sound silly to an adult, it could be a very frightening prospect for a young child and they may feel under pressure to carry out acts to protect themselves or family from further harm.

"The most fundamental piece of advice that I can offer is to speak with your children – let them know that they do not have to deal with any concerns on their own. It is crucial that parents are involved with their children’s online lives and I’d urge parents to make children aware of online dangers and ensure they know that they can speak to someone if anything or anyone online causes them concern.

“I would also advise parents to ensure that any devices used by your children are restricted to age suitable content. However, I am aware of media reports that the “Momo” challenge has popped up even when these controls are in place so there really is no substitution for supervising the games that children are playing and the videos that they watch online."

If adults are concerned or have any questions on how to approach the subject with their children you can contact the NSPCC Helpline on 0808 800 5000 or visit the NSPCC website.

Children who are feeling worried about their activity on apps or online games can contact Childline 24 hours a day, online and over the phone, on 0800 11 11 or by visiting www.childline.org.uk