Northern Territory police have used a Taser to subdue a 16-year-old boy they said was causing a “violent disturbance” at a Darwin high school.

But the boy’s mother, who witnessed the incident, told local media her son only became aggressive after an officer grabbed him from behind.

Police were called to Casuarina secondary college on Monday. They said in a statement officers “were faced with a 16-year-old male causing a violent disturbance and deployed a Taser on him in order to control the situation and ensure the safety of the attending officers, staff, students and members of the public”.

Guardian Australia understands the boy was allegedly in an altercation with another student and had displayed violent behaviour before the police were alerted.

The boy’s mother told the NT News she was in the school’s office with her son after being called to the school and he asked officers if he was under arrest. He then walked away and was angry but only became aggressive after an officer grabbed him, she said.

She said she would be making a complaint about the incident.

He has been charged with assaulting police and will appear in court on Friday.

The Department of Education said it was “unfortunate that a disturbance occurred” at a school which was “leading the way”.

“The safety and wellbeing of students, staff, parents and visitors at all schools is of highest priority for the department,” it said.

Tasers have been used by NT specialist officers since 2003 and were introduced to the kit of uniformed police in 2008. In 2009 a review was held after the death of a man in Alice Springs. The coroner found the use of a Taser against the deceased “premature and inappropriate”.

The stun guns have been adopted by police forces globally as a non-lethal alternative to firearms but Amnesty International said they had often been deployed “in situations where the use of a firearm would never be considered”.

The United Nations was last week set to issue a warning to the UK to stop using Tasers on children.