Seoul, Nov 18 : South Korean authorities on Tuesday began a joint forensic investigation into a boiler tower collapse at an Ulsan power plant that claimed seven lives.

The investigation team, which is made up of officials from the Ulsan Metropolitan Police, the Gyeonggi Nambu Provincial Police, the National Forensic Service, the labour ministry and other agencies, will look at debris from the collapse to find clues to the November 6 accident, Yonhap News Agency reported.

A total of nine workers were initially trapped when the 63-meter boiler tower crumbled at a thermal power plant run by Korea East-West Power Co., a state-run utility, in the southeastern city of Ulsan.

Two escaped with injuries, but the remaining seven were found dead.

The investigation is expected to focus on parts of the tower that were weakened as part of preparations to demolish the structure after 40 years of use ending in 2021.

The police and the labour ministry plan to combine the investigation results with testimonies from officials and construction-related documents to determine the cause of the accident and whether there were violations of the law.

On November 16, South Korean President Lee Jae Myung pledged to determine whether there were safety lapses at a thermal plant site in the southeastern city of Ulsan where seven workers were killed and sternly punished those found accountable.

â??As the person ultimately in charge of public safety, I am truly and deeply sorry,â?? Lee wrote on Facebook. "Despite the people's wishes, all seven trapped workers returned to their families as bodies. My heart is deeply torn."

Lee called the accident one that "should not have happened" and vowed to prevent similar accidents.

â??I will make sure that a tragedy like this is not repeated. We need to put an end to such a tragedy, where workplaces become a site of death.â??

The president called for a swift and thorough investigation to determine the exact cause of the accident and vowed to take stern punitive measures against those found accountable, regardless of their positions.

He also called on relevant ministries to review safety circumstances at work sites from scratch and take necessary safety measures during the winter season.

In a separate post on X, Lee wrote that rewarding people with merits and punishing those with faults is the basic principle of running an organization.

Lee's remarks were seen as supporting his administration's push to probe whether public officials were involved in illegal activities in connection with last year's botched martial law bid while simultaneously seeking measures to encourage civil servants.

On November 11, the government announced plans to form such a task force and unveiled a series of measures aimed at supporting active public administration and revitalizing the civil service community the following day.

/IANS