The Department of Labour says it will decide whether to lay charges in the next few days over the Pike River mine disaster.
Major investigations were launched by the department and by the police after 29 men were killed in gas explosions in the West Coast coal mine in November last year.
The department must lay any charges against the Pike River Coal company or individuals at the mine under the Health and Safety Act by the end of next week.
The department says its investigation is complete and the report is being considered by the deputy chief executive.
The most serious Health and Safety offences can lead to a jail term of up to two years, or a fine of up to half a million dollars.
Govt department to be quizzed again
While the Department of Labour's investiagtion is finished, the Royal Commission's inquiry into the disaster is about to enter its third phase.
As part of that it is recalling the department for another week of questioning.
The commission has released its list of witnesses for the start of the inquiry's third phase, which is to focus on why the West Coast mine exploded.
Nine witnesses are being called as the commission examines the external oversight of the mine and how the mine was operating.
The Department of Labour gave evidence to an earlier phase in July but three of its staff, including the two mines inspectors at the time of the disaster, will be called next week for more evidence.
Four miners will be called to explain the hydro-mining processes used at Pike River, including a Japanese expert and two former managers.
Police say their investigation is ongoing.