A 14-year-old girl was today locked-up for eight months after a video of her punching and verbally abusing a boy went viral online.

Dressed in her school uniform, the mobile phone footage showed the girl bullying the “vulnerable” boy, also 14, and hitting him in the face.

It emerged today that the assault happened while the girl was on a rehabilitation order for grievous bodily harm and witness intimidation.

Today, the youth court at Croydon Magistrates Court was played the video, which has been viewed more than 2.7 million times since being uploaded on May 14.

The girl had pleaded guilty to assault by beating at an earlier hearing.

Her parents looked on as the court heard that the girl “really struggles to restrain herself” when she gets “wound up”.

The video shows the girl, who cannot be named for legal reasons, grabbing the sweatshirt of the boy, who is several inches taller than her, and threatening him.

She strikes him on the side of his head and uses a racist slur before asking the boy: “Are you trying to p*** me off?”, adding that “I’m going to smack this yute.”

Police were alerted to the video about 15 hours after it was posted on May 14.

Her barrister, Kathryn Hovington, said the defendant had suffered a “public backlash” and “intimidation” following the video.

The girl was told by magistrate Ken Ashken: “This was an extremely unpleasant assault by you on a vulnerable 14-year-old who did not seek to respond in any way.”

She was sentenced to an eight-month detention and restraining order for the GBH and witness intimidation and a further four months for the assault, with the sentences to run concurrently.