Another Irish backpacker is in a critical condition in hospital after being bashed at a Sydney beachside suburb, police say.

Gearoid Walsh, 23, was rushed to hospital about 11pm (AEDT) Sunday when he stopped breathing following an attack at Coogee.

"Police believe Gearoid had been drinking at hotels in the area before he got into an argument with a man at a takeaway food shop on Arden Street," police said in a statement.

"Initially, Gearoid left with his brother, but returned moments later and the argument continued.

"The man punched Gearoid who stumbled and fell, hitting his head on the ground."

Since then, Mr Walsh has been on life support in hospital. His mother arrived from Ireland on Wednesday.

News of the attack is reminiscent of the bashing in August last year of Irish tourist David Keohane, now aged 30.

The young Irishman, who had been working in Sydney as a flooring contractor, was left suffering serious head injuries at Coogee after a night out.

He was flown home, still unconscious, the next month and woke in April this year.

While police have made arrests over the bashing of Mr Keohane, investigators are now seeking Mr Walsh's attacker.

CCTV footage taken on Sunday shows a man wanted for questioning over Mr Walsh's assault.

He is described as being of white/European appearance, 25 to 30 years old, 175cm tall, medium build, with short brown and slightly curly hair and a clean-shaven, round face.

The man wore a white T-shirt and jeans.

"This is a sad incident for the family," Detective Inspector Paul Simpkins said in a statement.

"Gearoid only arrived in Australia a month ago on a working visa and had been spending time between his brother's house in Brisbane and his sister in Randwick."

Insp Simpkins asked for anyone with information about Sunday's incident to contact Crimestoppers on 1800 333 000.