Police hunt adults who forced screaming children to fight in brutal YouTube 'happy-slapping' film

The child in the dark shirt is repeatedly punched, kicked and even headbutted as he suffers a merciless beating.

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The adult who took the footage is clearly heard saying "smack the s*** out of each other".

In a brief lull in the fighting, he yells: "Stop hugging each other, little bitches."

He joins the light-shirted boy in giggling when the other child cries out after a blow to the face.

The three minutes and 34 seconds of film, entitled Lethal Fight 1, include a shot of the stronger child stamping on the other's head.

Later he delivers a vicious headbutt, to the delight of the unidentified cameraman who declares "Billy's getting gangster".

This is apparently a reference to the beating the child in the dark shirt is taking.

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In another disturbing scene, one of the children - neither appears older than 12 - turns to the camera and asks: "Kicking's allowed isn't it?"

Police believe the film was taken in West Sussex because one child is heard to chant "Crawley, Crawley Town".

Officers are investigating a second film, Lethal Fight 2, which was also posted on YouTube and appears to feature the same children. Social services staff are helping the police try to identify the pair.

Detective Sergeant Richard Harris, of Sussex Police, said: "This appears to be a case of child cruelty and criminal behaviour by any adult involved in the making of this appalling video.

"Sussex Police child protection team and West Sussex young persons' services team will be working together to safeguard the welfare of the children and prosecute any adults involved in criminal behaviour."

A spokesman for West Sussex County Council said: "The [videos] will be forwarded to the appropriate child care team to see if the children in the films are known to us.

"The welfare of children is paramount to our children and young people's services and if they are known to us, we will take whatever action is appropriate."

Last April, four Plymouth women narrowly escaped a jail term for forcing two toddlers to fight "like dogs" in front of a video camera.

The women admitted goading a two-year-old boy and a three-year-old girl to hit each other.

YouTube, one of the world's most popular websites, allows users to upload clips for viewers to rate.

Last November, it carried a video of a 25-year-old mother being gang raped at her home in South London in front of her two crying children.

It was viewed more than 600 times before it was removed and reported to police.

Last month, internet safety experts told MPs that YouTube should be prosecuted for carrying "happy slapping" clips, in which violent attacks are filmed on mobile phones.

A YouTube spokesman said last night the firm would cooperate with the police inquiry.

He added: "YouTube is a community site used by millions of people in very positive ways.

"Sadly, as with any form of communication, there is a tiny minority of people who try to break the rules. On YouTube, these rules prohibit content like pornography or gratuitous violence.

"When people see content that they think is inappropriate they can flag it and our staff then review it.

"If the content breaks our terms then we remove it and if a user repeatedly breaks the rules we disable their account.

"If the police ask us for information, we will cooperate, so long as they follow the correct legal process that the Government introduced."

A YouTube source said it was impossible to review every video because ten hours of footage are uploaded every minute.