The plain clothed officer who tackled a 14-year-old First Nations child to the ground, causing them to sustain serious head injuries, should be referred to the Director of Public Prosecutions, says the lawyers who made the complaint.

It comes as the Redfern Legal Centre (RLC) argues NSW police use force against First Nations people at vastly disproportionate rates.

The Law Enforcement Conduct Commission (LECC) launched Operation Mantus after complaints by the RLC about the arrest of an Indigenous child, known as YPM1.

The teen suffered a serious head injury during his arrest, which required an overnight stay in hospital, after being tackled to the ground by police officers during an arrest on September 11, 2022.

Despite having a visible and bloody head injury, and before emergency services treated them at the scene, YPM1 was forcibly walked and handcuffed by police, who were not wearing body-worn video (BWV).

The LECC investigation primarily focussed on YPM1's initial apprehension, as well as other issues arising during the period he was in custody after the arrest.

National Indigenous Times reported on Monday the child was questioned by police despite informing his Aboriginal Legal Service lawyer that he wanted to exercise his right to silence.

The LECC was critical of police not wearing BWV and found the officers should have considered the removal of handcuffs after YPM1's identity was ascertained and the situation controlled.

However, the LECC didn't recommend criminal charges for the officer who arrested the child.

RLC police accountability lawyer, Samantha Lee, said she was disappointed by the findings, which found the arrest was lawful and the force used was not excessive.

"My client, a child of slight frame, was tackled to the ground by a physically robust adult male police officer," she said.

"As a result, he sustained a horrific head injury."

She said it was shocking that the NSW police have no procedures in place that guide the use of force against children and young people.

Furthermore, Ms Lee said the NSW police use force against First Nations people at a vastly disproportionate rate.

"We've obtained records that show First Nations people were involved in about 45 per cent of the use of force incidents," she said.

"The NSW police have a systemic problem that requires a systemic solution."

The LECC in Operation Mantus made 19 recommendations, despite not recommending criminal prosecution.

The included the BWV Standard Operating Procedures being amended to make clear that they apply to police conducting operational duties in plain clothes; Police training and ongoing education materials with respect to use of force including specific content and guidance on the handcuffing of persons - in particular children and young persons; and a review of the police policies and procedures to emphasise the need for officers to obtain prompt medical attention for people who have sustained injuries following the use of force by police officers.

The RLC said they welcomed the recommendations, but more robust reforms were needed.

They called on the police minister and Police Commissioner to immediately cease the use of handcuffs on injured children and introduce robust reform that deals with the systemic use of force by the police.

"The Police Commissioner must address the use of force against First Nations people and children at all levels of the police force," Ms Lee said.

"We urgently need a comprehensive and public inquiry into the use of force by police."