The name of a hoax online 'challenge' which frightened children has appeared on a list of words and phrases blocked from email servers at County Hall.

The 'Momo challenge', which was widely reported earlier in the year, was believed to be an online 'game' featuring an avatar of a pale female doll-like figure, with dark hair and bulging eyes.

Reports circulated that it was targeting young people through messaging apps, videos and social media and challenging them to harm themselves or others - but experts and charities, including the NSPCC, later said it was nothing more than a hoax.

But a Freedom of Information request has revealed the name of the hoax is banned from servers at Norfolk County Council, under three different forms.

'Momo' 'mo mo' and 'm0 m0' are all blocked from reaching any council-registered email address, including those of councillors, officers and employees of any council department, including education and children's services.

A spokesman at County Hall said: 'Norfolk County Council receives thousands of emails a day. Like many large organisations, the council blocks emails that contain words that could be phishing emails to trick or scam people, as these could compromise the security of our IT systems.'

Norfolk County Council was asked by the local democracy reporting service what had specifically led to the blocking of this phrase in particular.

It was also asked what impact the phrase's banning would have on any families attempting to contact children's services with concerns or seeking advice.

Norfolk County Council said: 'We have nothing further to add to our response.'

The Momo challenge originated in Mexico in 2016, but came to prominence in the United Kingdom at the beginning of this year.

It saw several schools around Norfolk and Suffolk write to parents with advice.

However, Paul Maskall, former cyber security advisor to Norfolk police and owner of cyber security consultancy Jungo, said in February it was 'an indisputable hoax'.

He compared it to Blue Whale, an internet 'game' challenging teenagers to do increasingly dangerous things which went viral in 2016.