The mother of an Irish backpacker, who was fatally bashed in Sydney at the weekend, says her son did not die in vain, because he was an organ donor.

Tressa Walsh says she is heartbroken for the man her son was fighting with and does not blame him for what happened.

Mrs Walsh flew to Sydney two days ago, after she found out her son Gearoid Walsh was in a critical condition in hospital.

He got into a fight at a Coogee kebab shop on Sunday night.

The 23-year-old was allegedly punched and hit his head on the ground. He died overnight in hospital.

Mrs Walsh told reporters this morning that her son was a "quiet and very introverted young man" who was not a fighter.

She called for her son's attacker to come forward, but said she did not blame him and did not want him to serve time in prison.

"We don't want him to torture himself over this," she said.

"We don't see this as a murder. Gearoid was very tall. He was six foot two, he had a long way to fall.

"I think [the other man] was just very, very unlucky. Myself and my family are appealing for him to come forward and get closure on this and some peace."

Mrs Walsh said her son had come to Australia from Dublin because his brother, who lives in Brisbane, had got him a job.

She said he had only been in Australia for a month, but it was the happiest month of his life.

"The most positive thing out of this, is that through his organ donation Gearoid has given several other Australians life," she said.

"That has given meaning to this awful incident."

Mrs Walsh said her family was devastated at the 23-year-old's death.

"Three years ago I lost my husband; my family have lost an adored son, brother and uncle," she said.

"My family hopes that Australians will help us by coming forward to police with any information as to what happened last Sunday night."

Police yesterday released security camera footage of the man they want to speak to in connection with the assault on Mr Walsh.

He is described as aged 25 to 30 years old, of average build, 175cm tall with short brown, slightly curly, hair.

Detectives are urging witnesses to come forward to Crimestoppers on 1800 333 000.

Alcohol concerns

Health experts say alcohol-fuelled violence will continue to increase until there is stricter enforcement of responsible service of alcohol laws.

Gearoid Walsh's death comes just over a year after another Irish tourist, David Keohane, was brutally assaulted in Coogee.

Mr Keohane spent seven months in a coma before awaking on St Patrick's Day in what his family described as a miracle.

The head of the National Preventative Health Taskforce, Rob Moodie, says alcohol-related deaths are unacceptable and can be prevented.

"For too long we've just let that go, really not paid any attention to it," he said.

"Licensees need to lose their licence if they don't manage it properly - that would very quickly change their attitude."

ABC News