New Zealand sporting great Sonny Bill Williams has added his voice to those showing support and concern for the group of Muslim students at Otago Girls' High School who were attacked on campus last week.

Hoda Al-Jamaa, 17, was sitting with her friends at the school when three other girls asked them how to swear in Arabic and started taunting them.

The situation escalated and Hoda's hijab was ripped off and she was hit while others filmed her.

"Two of the girls held me and one hit me and after I fell on the ground, she... was still hitting my face and my body. I was waiting for the teacher to help me," Hoda said.

The girls then took her hijab off and continued filming her.

Williams, an outspoken and devout Muslim, took to social media late on Thursday night to help bring light to the incident and morale support for the girls involved.

"Just a quick message of support to my sisters out there that are struggling with the hijab at the moment, in particular in India and of recent, Otago Girls' High School in New Zealand.

"Yes, these thugs may rip your headscarves off your head, but they'll never rip Islam or Allah from your hearts, so stay strong sisters. Inshallah, inshallah these thugs are met with the full force of the law," Williams said in an Instagram video.

Hoda said during the altercation that she was hit in the head so much she had to go to hospital for concussion, which now makes learning very hard, although she was very hesitant to go back to school.

It was not the first violent attack she had been involved in and she frequently had the fingers pulled at her and called a terrorist by other students, she said.

In a statement, police said the attack took place on Wednesday, 9 February and confirmed a group of Muslim pupils were attacked by three females aged in their early teens.

"The altercation and the possibility of the video circulating on social media is very concerning to us. The three alleged offenders have been identified, and an active investigation into the incident is underway.

"This altercation has caused significant disquiet and distress for the girls, their families, and the wider Muslim community. We are treating this incident with the utmost urgency and care.

"Violence or threatening behaviour including any involving hate, hostility, or prejudice regarding race, faith, sexual orientation, gender identity, disability, or age is not acceptable."

In a statement, Otago Girls' High School principal Bridget Davidson said, "I can confirm that we have strong pastoral care and disciplinary processes that we work through to understand every side of every story.

"Interpersonal situations are inherently more complex than they may appear on the surface and so need to be handled sensitively, fairly, and with the young people at the centre of the process and decisions."

Meanwhile, a petition calling for Otago Girls High School to take action against the students involved in instigating the attack, as well as providing more support for the victims, has garnered over 40,000 signatures.

Earlier on Friday, US supermodel Bella Hadid also took to Instagram in support of the victims, saying the story made her angry and sick to her stomach.

"We need to change this mindset of immediate judgement. teach our friends, children, parents, families that wearing a hijab, being Muslim, or being anything other than white in general, does not equal being a threat or different than anyone else. Teach them to love before hate. To educate before judgement. To protect before bullying [sic].

"I am so sorry to the ones that have felt this kind of disrespect. You do not deserve it. Keep your faith. Love your God. Be you. And the ones who appreciate and love you for YOU are the only ones that matter. It's not you, it's them. Remember that. I love you," she wrote.

- with RNZ