Sohn Jae-il, chief executive officer of Hanwha Aerospace, visits a joint memorial altar for vicitms of the explosion at the compnay's plant in Daejeon, Friday. Yonhap

The chief executive officer of Hanwha Aerospace has been booked over a deadly explosion at one of the company's plants last week, labor authorities said Monday.

Sohn Jae-il is suspected of violating the Serious Accidents Punishment Act in connection with the June 1 explosion that killed five workers and injured two others in the central city of Daejeon, according to the Daejeon Regional Employment and Labor Office.

The Daejeon police said they have separately booked Ga Jae-woong, the head of the Daejeon plant, over alleged professional negligence resulting in death and injury.

Ga was earlier booked by the labor office on suspicion of violating the Occupational Safety and Health Act.