Candlelight vigils and rallies were expected in South Korea on Saturday to commemorate the 156 people killed in a Halloween crowd crush, with public anger growing over one of the country's deadliest peacetime disasters.

The victims, mostly young people, were among the estimated 100,000 that had flocked to the capital Seoul's popular Itaewon nightlife district to celebrate the first post-pandemic Halloween.

South Korean law enforcement officials have conceded that there was insufficient safety planning for a crowd that large, and opposition politicians have accused President Yoon Suk-yeol's government of not taking responsibility for the disaster.

Reflecting that anger, a woman identified by local media as the mother of one of the victims was seen ripping apart the floral wreaths left by the president and Seoul's mayor at a memorial on Friday.

"What's the point of (these flowers) when they couldn't protect (our children)? Think about it," she was seen saying in footage broadcast by local TV stations.

"What's the point of standing next to these (wreaths) when you let our babies die?"

Uniformed police officers were then seen escorting the woman away from the memorial, located outside Seoul City Hall.

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President Yoon on Friday joined other top officials – including the national police chief and the interior minister – who had apologized over the disaster.

• South Korea begins probe into Halloween crowd surge

"As a president who is responsible for the lives and safety of the people, I am deeply saddened and sorry," he said.

"I know that our government and I... have a huge responsibility to ensure that such a tragedy never happens again."

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- Scrutiny of crowd management -

Yoon – who is with the conservative People Power Party – has been battling record-low approval ratings since taking office in May, and his political opponents are now taking aim at his government over the Halloween crush.

A civic group linked to the main opposition party was set to hold candlelight vigils across the country on Saturday evening, including in Seoul, Busan, Gwangju and Jeju.

A group of young Koreans was expected to hold a separate commemoration in central Seoul.

"I can't believe people of my age died just because they wanted to have some fun on Halloween," said Park Tae-hoon, 29, one of the organizers of that rally and a member of the progressive Jinbo political party.

"It was only yesterday that the president apologized," he told AFP, adding that the purpose of the march was to demand punishment for those responsible and measures to prevent a recurrence of the tragedy.

South Korea is in a period of national mourning that ends Saturday, with flags flying at half-mast and entertainment events cancelled.

Public scrutiny of how the Halloween crowd was managed is mounting, and a wide-ranging probe is under way into the exact cause of the crush.

With no single organizer for the Halloween celebrations, the government did not require any of the bars, clubs and restaurants – some located on Itaewon's narrow alleys and side streets – to submit a safety management plan.

And even though police had estimated beforehand that a crowd of 100,000 would participate, they only deployed 137 officers – compared with the 6,500 sent to another part of Seoul that night for an anti-government protest a fraction of the size.