Shocking footage of a mother watching her daughter brandishing a knife during a school playground fight has emerged.

The woman can be heard encouraging her to ‘stab the b***h’ as the pair brawl in their school uniforms, reports mirror.co.uk.

The teenager was allegedly handed a knife by her mum before the fight, tucking it in her trousers.

She can be seen pulling it out mid-way through the tussle.

The clip was recorded on video outside a school in Brazil, while onlookers were forced to stand and watch.

An injured 13-year-old school girl suffered slashes to her face, arms, hands and chest.

She was treated in hospital for her wounds and examined by forensic police investigating the incident.

Her opponent, aged 14, was said to have received minor bruising and scratches.

The two girls are meant to have been best friends who fell out following a disagreement over a video posted on social media.

The incident was registered with police and the mother, named as Elaine Santiago, is being sought for questioning by detectives over her apparent involvement.

She is alleged to have passed the knife to her daughter and deliberately stood in the way preventing others from intervening to stop the fight.

At one stage, as the pair rolled on the floor, she appears to step in to pull the victim off her daughter by her hair.

She has disappeared with her child and is facing charges of being an accomplice to attempted murder.

The fight apparently broke out in the middle of a road outside the gates of Nossa Senhora das Graças school in Belem, north Brazil, on 6 June.

The footage, which has just emerged, shows the moment two adolescents viciously batter each other grabbing clumps of hair and lashing out with their fists.

The clash turns deadly when one of the teen aggressor’s pulls out a knife and stabs her opponent delivering more than a dozen blows to the back, chest, face and arms.

The tussle is brought to an end when the woman, seen dressed in shorts and a yellow top, appears to whip the knife from the assailant’s hand, believed to be her daughter.

According to eye witnesses, the weapon was allegedly passed by the woman to the girl before the fight.

The teen reportedly tucked it into her trouser waistband and can be seen pulling it out midway through the brawl.

The aggression was said to have been ‘encouraged’ by the mother who urged her daughter on shouting at her to ‘stab the b***h’.

Others who tried to separate the students were forcibly pushed out of the way and told to stay back.

Speaking to Record TV, the mother of the victim, who did not want to be named said: ‘The fight started because someone sent a video in a WhatsApp message group used by the friends and made a joke about it.

‘One of them didn’t like what was being said about the film and they started to argue in the group.

‘Then the girl, who didn’t like the comments, warned she was going to ‘wait for her’ after school.’

Locals condemned the mother for her actions with many saying her example ‘was preparing her daughter for a violent future with an outcome of either ending up dead of behind bars’.

A spokesperson from the education department confirmed the altercation took place between two students outside the school’s grounds.

They said the school was disappointed with the students’ behaviour and ‘social workers and school psychologists are working with one of the families involved and attempting to contact the other’.

‘We have a schools’ programme that aims to combat violence among students and promotes educational actions against bullying,’ they added.

However, the mother of the victim argued that her family no longer feels it’s safe for the injured student to return to the school.

‘We have taken her out and we are trying to get her into a different one, so she can start afresh and continue with her lessons without having to face this animosity again,’ the mother said.