The police watchdog is probing a complaint over the alleged treatment of a teenage boy outside a night club in Co Tyrone last weekend.
The 16-year-old was arrested on suspicion of assaulting police.
A video clip reported on by the Irish News newspaper appears to show a uniformed police officer kick the teenager about the head while he is being held on the ground.
A spokesperson for the Office of the Police Ombudsman confirmed they have received a complaint, which they will be investigating.
They added that the officer was also notified of the matter by the PSNI.
Solicitor Gavin Booth of Phoenix Law, who is acting for the teenager, said they would say the “actions of the officers are wholly unacceptable and reprehensible”.
“We call on the PSNI to immediately suspend this officer from duty,” he added.
It is understood that no police officers have been removed from duty.
Sinn Féin MLA Linda Dillon said the incident was “disgraceful and totally unacceptable”.
Ms Dillon added: “I have been made aware of footage appearing to show a 16-year-old boy being kicked in the head by a police officer during arrest.
“This is deeply concerning and should be referred to the Police Ombudsman immediately for investigation. The PSNI must also consider appropriate action.
“I will also be raising this at the Policing Board.”
A police spokesperson said a 16-year-old boy was arrested on suspicion of three counts of assault on police, following a disturbance in Cookstown in the early hours of Sunday December 8.
“The disturbance occurred after patrol officers stopped to assist an injured man in the James Street area,” they said.
“The boy was later released on bail to allow for further inquiries.
“The Police Service of Northern Ireland have notified the Office of the Police Ombudsman of this incident and as such it would be inappropriate to comment further at this time.”