Police have warned parents that the online character 'Momo' has returned with a vengeance and is being inserted into versions of the viral 'Baby Shark' videos.
The 'Momo Challenge', which made headlines last year, saw WhatsApp users enticed to contact 'Momo', a scary looking female figure with bulging eyes.
After contacting the character, users were said to receive graphic images along with instructions to perform dangerous tasks that even included suicide.
Spanish police believe sick netizens are bringing Momo back to life by dropping it into 'Baby Shark' videos
However, while the WhatsApp version of Momo has been reported in the media as being a hoax, Spanish police believe sick netizens are bringing the character back to life by dropping it into 'Baby Shark' videos and other social media clips aimed at children.
A police social media campaign warned parents: 'No, Momo does not exist, it is an old viral character that has resurfaced with some damaging modifications.
'We have to work together to not allow it to spread.'
The local authorities announced that they are investigating numerous online videos while asking parents to 'supervise what videos their children watch online, especially the younger ones'.
According to local media, there is one video which features the character saying: 'Hi, I am Momo. I want to play with you. Look for a knife in your kitchen and cut your little hands. If you do not do it, Momo will come after you.'
The police have asked citizens to report anything suspicious they see on social media immediately.
The 'Momo Challenge' made headlines last year for encouraging children to self-harm in videos