ACT Policing is calling on the public to help them find three men allegedly involved in the assault of that victim and another two men at about 1.20am on Sunday October 30.

In the footage, two groups are seen fighting in Bible Lane, next to Academy, and several punches are thrown.

One man then appears to approach the victim and punch him in the back of the head while he was facing the other way. The victim then falls to the side.

The three alleged offenders then ran off.

The victim suffered facial injuries and had emergency surgery at the Canberra Hospital, Constable Jarrad Drennan said.

"His jaw was broken and he received three metal plates as part of the surgery to reconstruct his jaw," he said.

"It's a sickening act and we won't tolerate it in the ACT."

The three men allegedly involved in the assault are described as Caucasian.

The one who police say threw the punch is described as 170cm (5"7') tall, of slim build with brown hair. He was wearing a green pin stripe long-sleeved shirt, dark pants and brown shoes.

The second man is described as 180cm (5"11') tall, of medium build with brown hair. He was wearing a white long sleeved shirt and dark trousers.

The third man is described 185cm (6"1') tall, of medium build. He was wearing a pink shirt, dark trousers and a blue baseball cap.

Police are urging anyone who may have witnessed the incident who have not yet spoken to police, or who can identify the offenders to contact Crime Stoppers on 1800 333 000, or via act.crimestoppers.com.au. They should quote reference 6029089. Information can be provided anonymously.