This means the death toll could stand at seven.
"Unfortunately, we must assume we will not find the five missing people alive," Currenta CEO Frank Hyldmar said at a press conference.
Four of them are Currenta staffers, Hyldmar specified, extending condolences to families.
The blast occurred on the plant belonging to the Currenta company on 27 July. It is not yet known what caused the explosion. However, it was established that a cistern exploded at a waste treatment and storage centre.