The accident happened on the construction site in Puttgarden, Germany.
The accident is being investigated by the authorities and Fehmarn Belt Contractors (FLC). Femern A/S will provide updates as more information becomes available.
The 18km-long immersed tunnel beneath the Baltic Sea will connect Rødbyhavn on Lolland in Denmark and Puttgarden on the German island of Femern. Earlier this month dredging was completed for the tunnel trench.