Amid a heavy police presence at the constitutional court, some relatives attending the hearing broke down in tears after the ruling, with two mothers collapsing and taken away by an ambulance, reports say.

The official, who was only identified by his surname Jeong and in charge of intelligence affairs at the Yongsan Police Station covering Itaewon, was found dead at his home by a family member, reports say.

At least 156 mostly young people were killed, and scores more injured, in a crush at the first post-pandemic Halloween party in Seoul's popular Itaewon nightlife district.

The transcripts of emergency calls released by the police showed the first warning of a possible deadly surge was made roughly four hours before the crush turned deadly.

The death toll from the crush at a crowded Halloween street party climbed to 156 with 151 injured, 29 of whom were in serious condition.

Officials say 154 were killed and 149 injured, with 33 people in serious condition.

Twenty-four hours before, there were already warning signs that the festivities were attracting dangerous numbers of people, and victims and their relatives questioned an apparent lack of crowd control.

Local media reported that the suspect told authorities he 'wanted to kill people so he could be sentenced to death'.

The suspect had spoken of carrying out such a crime five years ago had no criminal record.

The Los Angeles County Department of Public Health is discouraging traditional festivities and recommending socially distant alternatives.