Yonhap news agency reported that a crane collapse in a South Korean shipyard killed six people and injured more than 20 others.
Rescue workers have been looking for trapped personnel after an accident in Geoje near Busan on Monday.
It is understood that the victim is a subcontractor working for the shipyard Samsung heavy industry.
The incident shocked South Korea, where the incidence of industrial accidents was relatively low.
The oil platform was built for the French company Total for the Martin Ringle field in the North Sea of Norway.
Total spokesman Leif Harald Halvorsen told Yonhap: "The Crane landed on the well bay module of the platform where people are working . ".
"At the moment, all the work in the yard has been stopped and the investigation is in progress.
He added that there were not all employees among those who died or were injured.
Samsung Heavy Industries is the world's third-largest shipbuilding company and has also participated in other projects.