The Prime Minister is standing by his statement, reported in The Australian newspaper, that the way the Pike River mine was constructed would not have been legal in Australia.
Twenty-nine men were killed in a series of explosions in the West Coast coal mine last November.
At the time, John Key said safety standards in New Zealand were similar to those in Australia. However, in an interview with The Australian newspaper published on Tuesday, Mr Key said the Pike River Mine, which is a single-entry mine, could not have been constructed in Australia because it would have been illegal.
Mr Key says there is a difference between safety standards and construction standards, and he stands by his comments.
A Royal Commission into the mine disaster begins sitting on 11 July.
Labour Party leader Phil Goff has accused Mr Key of performing an about face, saying he has changed his tune about not commenting until the Royal Commission is complete.
Comments 'too late' says family
The mother of one of the Pike River mine victims says it makes no sense that there was only one way out of the mine and only one ventilation shaft.
Joanne Ufer's son, Joshua Ufer, was one of the 29 men killed in the mine and she told Checkpoint the Prime Minister's comments have come too late.
Ms Ufer hopes the Royal Commission into the disaster will push forward changes to New Zealand's mining industry.
