Royal Commission hearings on the Pike River mine disaster have been delayed by almost two months, until 11 July.
The commission says the extensive investigations being conducted by police and the Department of Labour will not be concluded for some months.
It says there are some difficulties in using evidence collected by those agencies while their investigations are current.
Also delaying the hearings are the financial difficulties of Pike River Coal, which is in receivership.
The company has indicated that because of this it is unable to play a full part in the inquiry.
The commission says it had worked on the assumption Pike River Coal would be fully involved.
The delay in the Royal Commission hearing will have a flow-on affect, delaying the examination of issues such as what happened at the mine and how the search and rescue operation was conducted.