Filmed in Hartlepool, one clip shows a girl being brutally attacked by another and is then left unconscious, before a man appears to kick her as she lies on the floor.

The video, which lasts more than two minutes, then shows friends crowding around the girl before making a desperate 999 call for an ambulance.

Another 41-second clip posted on video sharing website YouTube by the same person shows a girl kicking and stamping on another's head as she is laid on the floor.

A voice can be heard to shout "go on" during the clip filmed in the doorway to someone's home, before the attack moves into the street outside.

The video, entitled "Vicky stampin on Kim's head lol", has been posted by someone under the name "ilovedrink09", and there are a number of other clips under the same name.

Police say they are investigating the films and have appealed for anyone who has any information on the people involved to contact them.

It follows a similar case where a film clip called Milton Road Fight Club was posted on the site which showed a victim being kicked unconscious by a thug as a crowd watched. The clip, which showed a man being chased down the street by another man before being attacked and kicked to the head while on the ground, has since been removed from the website.

Cleveland Police launched an investigation into the clip, and town MP Iain Wright brought the issue up in the House of Commons.

Mr Wright said at the time: "I'm concerned that acts of violence and instances of happy-slapping recorded on mobile phones are transferred to the web.

"Acts of violence should not be tolerated and should not be glorified on the internet."

A Cleveland police spokeswoman said: "We are investigating the incident."

Anyone with information on the latest clip can contact Hartlepool Police on (01642) 302126.