A second officer is under criminal investigation for assault after an incident at Manchester Airport, the police watchdog has said.

Video which showed an officer kick and stamp on the head of Fahir Amaaz, 19, as he and his brother Muhammad Amaad, 25, were restrained by officers led to protests in Rochdale and Manchester city centre after it emerged last month.

More footage, obtained by the Manchester Evening News, emerged days later which showed the immediate lead-up to the disturbance on July 23, when two female police officers were hit to the ground before Mr Amaaz was tasered.

In a press conference earlier this week, the family’s lawyer claimed the men’s mother, Shameem Akhtar, 56, was hit in the face with a Taser by an officer.

In the days after the incident, the Independent Office for Police Conduct (IOPC) announced a Greater Manchester Police (GMP) constable was under criminal investigation for assault in connection with the arrests of the brothers.

In an update on Thursday, the watchdog said a second officer had been advised they were also under criminal investigation for assault, relating to an incident shortly afterwards when two other men were arrested.

The officer is also being investigated for potential gross misconduct for alleged breaches of police professional standards including their use of force.

An IOPC spokesman said it had received a further referral from GMP of a complaint, detailing several allegations, from one of the people involved.

IOPC regional director Catherine Bates said: “It is clear the situation at Manchester Airport was complex and escalated rapidly.

“The incident, which resulted in injuries to police officers and members of the public, has caused understandable concern and we are working hard to piece together all of the relevant events on that day.

“In parallel, Greater Manchester Police is investigating whether any criminal offences were committed by members of the public during the initial altercation and the subsequent arrests.

“These investigations are separate, and we are liaising with the Crown Prosecution Service to establish how they can progress in parallel.”

The IOPC spokesman said its investigation will consider whether discriminatory behaviour may have influenced the treatment received.

It will look at the force used against six members of the public in two incidents, the first involving the arrests shown in footage and the second, shortly afterwards, when two other men were arrested and one was Pava sprayed.

It will also consider allegations about the level of care provided to a woman who reported she received an injury during the arrests and a young child present at the time; the language and level of force used by police towards two of the men who were arrested; and the men’s subsequent detention in custody.

Four men were arrested on suspicion of affray and assault following the incident and were later bailed.