Tens of thousands of people — mostly in their 20s and 30s — had been out enjoying post-pandemic holiday festivities in Seoul's Itaewon district at the time of the disaster. 

The night turned deadly when people poured into a narrow, sloping alleyway between bars and clubs, the weight of their bodies and a lack of effective crowd control leaving more than 150 crushed to death. 

A year on, victims' families say they are still seeking answers to what went wrong and who was responsible for the deadly crush.

"We did not want to become bereaved families," Lee Jung-min, who lost his daughter to last year's disaster and now leads the families' group, said during the rally in Seoul.

"Why do you think the 159 victims who lost their lives in the Itaewon disaster had no choice but to become stars in the sky?" he asked, adding: "I would like to hear an answer to whether you think the government is not responsible."

A police probe into the disaster found massive failures in planning and a botched and delayed response to the unfolding catastrophe.

But it stopped short of assigning blame to any top officials, and no senior figures were fired or resigned over the disaster.

Lee Ju-hyun, a survivor of the crush, said she had regularly been visiting the site of the disaster since last year.

"Some people say I'm lucky, but then, did 159 people have to die because they were unlucky? Was this something where luck had to determine life or death?" she asked the crowd.

"I will always be here with them," Lee said, adding: "Just because some try to ignore it, it doesn't mean it never happened.

"I will always be standing here. I will continue to be a survivor".

Saddest day

Around 10,000 people were expected to attend Sunday's commemoration, according to the families' group ahead of the event, including the victims' families, survivors of the crush, activists, as well as lawmakers and government officials.

Despite being invited, President Yoon Suk Yeol did not attend the event, which his office dubbed an opposition "political rally", according to local media.

Instead, Yoon attended a service commemorating the victims at a church in Seoul and expressed his condolences there.

"This day last year was the saddest day of my life, and I believe everyone in South Korea feels the same way as me," Yoon said during a speech at the church.

The South Korean president highlighted his government's efforts to build a "safe" country over the past year and vowed to work harder, adding: "We must make sure the sacrifices of the victims will not go to waste."