Cleveland Police said there was no truth in a report - which has gone viral on social media networks - that said a two-month-old white baby was punched in the face and thrown against a wall by an Asian youth in a Teesside street.
In fact, the story appears to be loosely based on a 2005 incident in which a ten-month-old Asian baby was punched in the face and chest by a drunken white youth in Middlesbrough.
Police are understood to be examining whether the hoax is racially motivated and if any action can be taken.
It was posted by a website, The Daily Bale (Britains Against Left-Wing Extremists), which has links to far-right groups, and the story has spread across the Internet, posted by people believing it to be true.
Disturbingly, it also appears to have used a picture of a tiny baby taken from a petition against child abuse.
It also makes up quotes from a serving police officer who investigated the true incident in 2005.
A spokeswoman for Cleveland Police said last night: “We are aware of posts circulating across social media claiming that a baby was assaulted by an Asian youth in Middlesbrough last week.
“These reports are a hoax and an incident of this nature has not been reported to police. We would ask that people do not retweet or share the posts.
“An officer will be looking at where this originated and seeing if any action needs to be taken.”
Even extreme far-right groups were quick to condemn the hoax last night.
The English Defence League originally shared the story, but later wrote on its Facebook page: “Please not that the article on the Daily Bale regarding a baby being assaulted is not true. The picture of the baby is from a petition on the change.org site relating to child abuse. Please do not post the link for the article on Facebook.”
British Patriots Society warned on its page: “Please be aware that the "Daily Bale" page and website is a troll page, and their stories are fabricated. I doubt very much that you'll find any of the stories from the Daily Bale that are true.”