Police have released shocking footage of a one-punch assault outside a Civic nightclub in the early hours of Sunday as the attacker remains on the run.
A man became aggressive after security staff at Academy nightclub on Bunda Street refused him entry at about 12.40am, police allege.
He had a brief conversation with a man standing beside him before he dealt a single blow to the man's head, causing him to fall backwards.
The footage shows the victim landed head-first on the concrete footpath as his legs buckled beneath him.
The offender appears to remain aggressive after the attack as bystanders rush to help the victim.
Police said the offender later fled east along Bunda Street with two other men.
The offender was described as a man of Pacific Islander or Maori appearance and about 193cm tall with a large build.
He was wearing a dark shirt, grey pants and a black cap printed with the word ‘compton’. He also had tattoos on his arms.
The victim was taken to The Canberra Hospital for treatment but was later released.
It's the second one punch attack to take place outside the Academy nightclub this year.
A man was left with a fractured skull and bleeding on the brain after a man levelled him with one forceful punch outside the club on April 21.
Confronting CCTV footage released following that incident showed the man appeared to argue with a group outside the club, before the victim walked away.
The man followed and caused the victim to fall to the ground with one swift blow to the head. The victim was knocked down and smashed his head on the pavement, leaving him unconscious and with serious injuries.
A Canberra court last week overturned the conviction of a Canberra man who punched a drunk Irish tourist in an early morning assault in Civic, leaving him with a serious brain injury.
Daniel Byrne, 21, will face a retrial in the ACT Supreme Court on a charge of recklessly inflicting grievous bodily harm.
Canberra teenager Tyran Pumpa is due to be sentenced in the same court on Friday after he floored a man with a single hit to the head during a night out in Civic in March last year.
He was committed to the higher court for sentencing after he pleaded guilty to inflicting grievous bodily harm in the ACT Magistrates Court.
The charge carries a maximum penalty of 13 years in jail.
Anyone with information about the most recent attack should contact Crime Stoppers, 1800 333 000 or www.act.crimestoppers.com.au. Information can be provided anonymously.