A 23-year-old Irish backpacker died in an Australian hospital last night following a vicious assault over the weekend.

Gearoid Walsh from Dublin suffered serious head injuries when he was attacked outside a fast food outlet in Sydney on Sunday and had been on life support ever since.

New South Wales Police last night confirmed to the Irish Independent Mr Walsh had "passed away overnight".

He had been in Australia for just one month when he was involved in a violent altercation with an unknown man.

Now police have released CCTV footage of a man they want to contact in relation to the assault in the hope locals in the area will identify the assailant.

Police are expected to await the results of a post mortem examination before deciding whether to upgrade their investigation to manslaughter.

"It is hard to say. It could change because the outcome is far more serious than assault. The sheer size of the investigation will increase because someone has lost their life," Sergeant Dave Rose of New South Wales police media told the Irish Independent.

Mr Walsh's mother rushed to Sydney to be at her son's bedside in the Prince of Wales hospital last night.

This is the latest violent assault involving an Irish citizen to happen in the same area of Sydney.

Last August, David Keohane from Ballyvolane in Cork ended up in a coma for more than six months following an attack in the suburb of Coogee while he was walking home from a party.

Police arrived in the Arden Street area late on Sunday night to find Mr Walsh in cardiac arrest after he had stopped breathing.

He had been drinking in a number of hotels in the area, which is popular with Irish backpackers, when he went into a local take-away shop with his brother.

It was here that he became involved in an argument with another man, after which the Walsh brothers left the take-away.

However, they returned a few minutes later and the argument continued, during which the man hit Gearoid. He stumbled and fell and hit his head on the pavement.

It is understood that this impact with the ground caused his main injury.

Last night, New South Wales police described the attack as a "fairly random, spur of the moment" incident and appealed for information about the man in the CCTV footage.

No arrests have been made, although the attack has received widespread media attention on news bulletins in the area, which local police hope will help them to track down the assailant.

Mr Walsh had been in Australia for the last month on a working visa and had spent some time with his brother in Brisbane, but was staying with his sister in Randwick, a Sydney suburb, when the attack happened.

"We would like to speak to the person in this CCTV footage as we believe he can provide us with information as to what happened," Det Insp Paul Simpkins said.

"This is a sad incident for the family. Gearoid's mother arrived from Ireland on Wednesday night. This is the last reason she would want to come to Australia.

"We urge anyone who may be able to identify the person in the CCTV footage to contact Eastern Beaches detectives."

Coogee is a picturesque area of Sydney, popular with Irish backpackers, and is well known for its nightlife, with a large number of bars and clubs in the area.

A spokesman for the Department of Foreign Affairs said the Walsh family was being given assistance by staff from the Irish consulate in Sydney.

Friends last night paid tribute to the dead man on his Facebook page.

"To our one and only beautiful friend Gearoid. Words can't even describe how we are feeling now. We have cried so many tears that would fill a river," one friend said.

- Shane Hickey and Denise Clarke

Irish Independent