A mother’s video of her son tearfully asking why school bullies had singled him out for torment prompted a worldwide flood of support, including from celebrities such as Hollywood actor Chris Evans, singer Demi Lovato and rapper Snoop Dogg.

Kimberley Jones posted the emotive clip of her son Keaton on Friday after picking him up from his school, in Knoxville, Tennessee, because he was too afraid to go to lunch.

In the footage, which has been viewed more than 22 million times on Facebook, Keaton asks: “Just out of curiosity, why do they bully? What is the point of it? Why do you find joy in taking innocent people and finding a way to be mean to them? It is not okay.”

The middle school student, which US pupils attend between the ages of 10 and 14, goes on to say his tormentors made fun of his nose, called him ugly and told him he had no friends.

After an emotional exchange with his mother, Keaton adds: “People that are different don't need to be criticised about it. It is not their fault. If you are made fun of, just don't let it bother you”.

In the post Ms Jones said Keaton had asked her to film the video after she picked him up and she asked the parents of the children responsible to “talk to your kids”.