Shocking mobile phone video posted on a social media site of an attack on a teenage girl by another female pupil at a Bingley secondary school was last night under investigation by police.

The clip, lasting one minute and 37 seconds, shows pupils surrounding a 14-year-old girl before she is pulled towards the ground by her ponytail and repeatedly thumped at Beckfoot School.

A jeering message accompanied the Facebook post of the video which has been described as an “exceptional and serious” case of cyber bullying.

Almost 900 people had ‘liked’ the video within two hours of it appearing and 595 users had shared the link.

Another post by the same girl asked who wanted ‘tagging’ – their name adding – to the video clip.

The public Facebook page had been removed yesterday but Beckfoot School was inundated with calls and e-mails.

Head teacher David Horn said: “We are aware of the incident and the school is taking appropriate action in line with its Behaviour Policy.

“We want to assure parents that we make every effort to ensure the school is a safe environment for their children and that we do not tolerate any unacceptable behaviour.”

Police yesterday intended to interview the victim, who received minor facial injuries during Tuesday afternoon’s attack.

Sergeant Paul Robinson, of Bradford District Youth and Schools, said: “We are taking this matter extremely seriously.

“Safer Schools officers are working alongside the local Neighbourhood Policing Team and the school to resolve the matter appropriately.”

Many people took to Facebook to vent their anger and encourage more people to complain to the school.

Charlotte Faulkner, 21, a trainee teacher who lives in Chester, but is formerly of Bingley, said she found the video particularly disturbing and has written to the school.

She said: “I had a friend who committed suicide a couple of years ago because of bullying. I saw the video. I just think it’s horrible.

“The most upsetting thing is that there’s a massive group of people just following and nobody’s helping the girl who’s on her own. I’m hoping that the girl is punished and made an example to everybody else at school,” she said.

Miss Faulkner’s letter read: “The video of the attack currently has 12,534 comments at this moment in time and 956 likes on the social media site, Facebook, and has become almost an internet 'sensation', which only outrages and disgusts me further.”

Councillor Ralph Berry, the Council’s executive member for chiildren and young people’s services described the incident as “exceptional and very unusual”, “It has to be taken very seriously and I know the school and head teacher is taking it seriously, it’s been reported to the authority and everything’s been done to follow it up,” he said.

Facebook would not comment to the Telegraph & Argus about the incident but it pointed out has a tool on every page where people can report offensive material. It employs a large team of staff who look at complaints and can remove posts of harassment and close people’s profile pages.

Beckfoot School’s website includes a section where prospective pupils can ask questions which are answered by current students.

It says: “The staff at Beckfoot are very good at quickly and effectively dealing with bullying when it occurs.”