WA man critical after alleged assault outside Bunbury nightclub

A West Australian man is fighting for his life in hospital after an alleged one-punch attack outside a nightclub.

The 23-year-old man was found unconscious in Bunbury, in the state's southwest region, at about 2.30am on Sunday morning.

Police say an argument happened at a nightspot in the town that has moved out onto the street.

"There was an altercation that took place at Fitzgerald's nightclub, it's spilt out into one of the streets in Bunbury where a 23-year-old male and a 21-year-old male have become involved in an argument," Sergeant Nick Hamer said.

"As a result of that, a 23-year-old victim has been taken to hospital – he's suffering critical injuries at this stage."

The alleged victim was taken to Bunbury Regional Hospital before being flown to Perth for further treatment.

The 21-year-old involved in the incident has been charged with grievous bodily harm and is due to appear in Bunbury Magistrates Court on August 31.