Footage of the man’s arrest was posted to social media, including a moment when one of the officers making the arrest appears to stomp on the head of the man as he lies on the ground, surrounded by other officers.

A police spokeswoman said a Senior Constable from the Critical Incident Response Team was last night suspended following his involvement in the incident, which started at the Northern Hospital at Epping.

“Professional Standards Command continue to investigate the matter and are currently assessing all available information,” the spokeswoman said.

Robinson and Gill principal lawyer Jeremy King, who is representing the arrested man, told the ABC yesterday his client, who was in an induced coma, had not committed a crime and was being treated for mental health issues at the time of the arrest.

“Really he’s a person that the police should be dealing with in a very unique way,” he said.

“They should be recognising that he’s a vulnerable person and this isn’t a situation … where police are pursuing an offender.”

King said yesterday that information on the injuries his client had suffered was “limited” and doctors were running scans to work out how much damage had been done.

Police are urging anyone who witnessed the incident or has footage of it to contact Crime Stoppers on 1800 333 000.

-ABC