A school in Hull has issued a warning to parents over the dangerous Momo challenge.
Northcott school in Bransholme has warned parents about the "nasty challenges" which appear in videos on YouTube.
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The so-called Momo Challenge purportedly features a disturbing image of a girl with bulging eyes and a crooked smile.
Reports of this image popping-up in the middle of child-orientated YouTube videos such as Peppa Pig have gone viral on social media.
It is then claimed the doll encourages children to add a contact on WhatsApp who then sends them violent images and dares.
The school's tweet read: "Important: we are aware that some nasty challenges (Momo challenge) are hacking into children's programmes. Challenges appear midway through Kids YouTube, Fortnight, Peppa Pig to avoid detection by adults.
"Please be vigilant with your child using IT, images are very disturbing."
However, Commons Leader Andrea Leadsom said on Thursday in Parliament that there was no confirmed evidence the so-called 'Momo challenge' genuinely poses a threat to British children.
Mrs Leadsom flagged up how charities were telling her there was "no confirmed evidence" Momo had led any children in the UK to self-harm.
She said: "We've been very clear that more needs to be done to protect young people online, including from cyber-bullying and suicide and self-harm content, and internet companies do have a responsibility to their users.
"The forthcoming online harms white paper will set out a range of legislative and non-legislative measures to keep UK users safe online.
"In the case of Momo, organisations including the Samaritans, the NSPCC and the Safer Internet Centre have said there is no confirmed evidence the Momo phenomenon is posing a threat to British children."
Whether the challenge is a threat or not there are several ways to protect your child online against potentially harmful material.
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Here's how to safeguard your children online:
The NSPCC, in partnership with O2, offers the following advice on online safety.
Use Net Aware: A guide to the social networks and apps your child might be using and practical advise over how to keep them safe.
Parental controls: Set up parental controls to block upsetting or harmful content, control in-app purchases and manage how long your child spends online.
Lots of mobiles, tablets and home broadband come with settings to manage what your child can and can't see or do online.
Online gaming: Activate safety settings on games consoles, turn off in-app purchases. Both the Apple app store and Google Play allow parents to create a pin code which must be entered before every purchase.
Internet history: Check your child's internet history by entering CTRL + H when the browser is open.
Child accounts: Create a child's account on windows PC and enable Family Safety settings which allows you to block websites.
If using Mac set up Screen Sharing so you can see your child's activity.