An Australian who survived South Korea’s Halloween tragedy has described the “slow and agonising crush” that claimed the life of his friend in the country’s deadliest crushing disaster.

Earlier in the night, Nathan Taverniti and his small group were excitedly dressing in costume and filmed themselves arriving at Seoul’s Itaewon district, noting in the video: “There are so many people here.”

What should have been a “fun, happy, free” night ended with two of his friends in hospital and one of them dead — a 23-year-old Australian woman Mr Taverniti said he was helpless to save.

At least 153 people were killed in the Halloween stampede, including one Australian and citizens from around the world.

The Ministry of the Interior and Safety said the death count could further rise as 37 of the 133 other injured people were in serious conditions.

Mr Taverniti said he was right there in the narrow alley where the crowd crush happened and “all I could see was a wall of people”.

“I just can’t believe it. I was in the front of where it happened,” he told South Korea’s Yonhap News Agency.

“There was no stampede,” he said.

“It was a slow and agonising crush.

“This crush was not caused by drunk people. It was a lack of planning, police force and emergency services.”

In a video later posted to TikTok he recounted how his friends were suffocated and crushed in the surge while others in the dense crowd were still oblivious to what was happening.

Nathan Taverniti breaks down on TikTok.

Breaking down in tears in the video, Mr Taverniti said he was stuck in the crowd when he heard his friend say she “couldn’t breathe”.

“My friends were being crushed in front of me and I couldn’t do anything about it,” he said.

“I watched as people filmed and sang and laughed while my friends were dying, along with many other people.”

Mr Taverniti managed to crawl out from a pile of people and tried to pull others out while calling for help.

“I was trying to pull people out because there was not enough police officers and nobody was doing anything to make the crowd stop.

“We were yelling, we were saying, ‘You have to go back, you have to turn around, people are dying.’

“But nobody was listening.”

“The situation could have so easily been avoided, but nobody would listen.”

Mr Taverniti said he spent Sunday desperately trying to find his friend’s body, searching for “hours and hours”.

He placed the blame on authorities who he said poorly managed the event and had not responded quickly enough when things went bad.

“I am sad, I am angered, I am at a loss,” he said on TikTok.

One of Mr Taverniti’s friends, Sydney woman Julia Cho, also posted online while fearing she may “never get my sister back” who was in ICU.

“I’m posting this here to raise awareness and to express my grief,” she said.

“This happened very early in the night. People were suffocating, toppling over one another and crushed.”

An estimated 100,000 people had gathered in Itaewon for the country’s biggest outdoor Halloween festivities since the pandemic began.

Authorities said thousands of people have called or visited a nearby city office, reporting missing relatives and asking officials to confirm whether they were among those injured or dead after the crush.

South Korean President Yoon Suk Yeol declared a one-week national mourning period on Sunday and ordered flags at government buildings and public offices to fly at half-staff.

“This is really devastating. The tragedy and disaster that need not have happened took place in the heart of Seoul amid Halloween (celebrations),” Mr Yoon said during the speech.

A man mourns at the street of the deadly stampede. Photo: Getty

Australia’s Department of Foreign Affairs and Trade confirmed it had been notified of the Australian’s death in Seoul on Saturday night, local time.

A spokesman said consular officials were providing assistance to the deceased’s family.

They are also working to help other Australians present at the event.

“The Australian government sends its condolences to the family and others affected by this tragic incident,” the spokesman said.

Prime Minister Anthony Albanese tweeted on Sunday before news broke of the Australian’s death: “Our sincere condolences for all affected by this terrible tragedy.”

Flowers laid in the alley in the popular lightlife district of Seoul. Photo: Getty

Ambassador to the Republic of Korea Catherine Raper joined Mr Albanese in conveying Australia’s condolences to the South Korean government, describing the incident as “tragic”.

“We ask all Australians in Seoul to check in with friends and family to let them know your whereabouts,” Ms Raper tweeted.

Australians concerned about the welfare of loved ones in Seoul can call the Department of Foreign Affairs and the Trade Consular Emergency Centre on 1300 555 135. Those outside Australia can call +61 2 6261 3305.

-with AAP