Ulsan: President Lee Jae Myung on Sunday 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 punish those found accountable.

According to Yonhap News Agency, Lee made the remark after authorities on Friday recovered the last of the seven workers who were trapped when a 63-meter tower at the plant collapsed on November 6. The bodies of the six others had been recovered earlier.

"As the person ultimately in charge of public safety, I am genuinely and deeply sorry," 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. He stated, "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."

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.