The disclosure relates to an apparatus for sealing a package. The apparatus comprises a sealing unit and an abutment between which a number of material layers are disposed to be clamped and sealed and fused together, wherein the abutment is connected to at least one elongate element which extends in a direction from the abutment towards and past the sealing unit, the elongate elements, beyond the sealing unit are disposed to be connected to at least one first operating element, and an operating unit is disposed to apply a force between the sealing unit and the first operating element so that these are moved in a direction away from one another and so that the abutment and the sealing unit are moved in a direction towards one another.