A year on after the incidents, Maritime New Zealand is laying charges in relation to the deaths of two workers at ports last April.
Atiroa Tuaiti and Donald Grant died on 19 April at the Ports of Auckland and 25 April at the Port of Lyttelton respectively.
The docking company Wallace Investments is being charged in relation to Tuaiti's death after he was crushed under a container while working on a ship.
The Lyttelton Port Company is being charged in relation to Grant's death after he was struck by coal being loaded onto a vessel.
The charges are being filed under section 48 of the Health and Safety Work Act which carries a maximum penalty of a $1.5 million fine.
Director Kirstie Hewlett on behalf of Maritime New Zealand said that everyone deserves to go home safely from work each day and actions are under way to improve port safety.