Prime Minister John Key says the country is in mourning after the Pike River Coal mine disaster.
Mr Key, speaking at a media conference at the Beehive on Wednesday evening, extended his sympathies to the families of the miners on behalf of all New Zealanders.
He said he will travel to Greymouth on Thursday to meet the miners' families as well as those involved in the operation to find the men.
Mr Key directed most of his remarks to the families of those who died, but also acknowledged those from Australia, Britain and South Africa who lost loved ones.
Flags will fly at half mast and Parliament, after paying its respects, will rise early on Thursday.
Governor General's condolences
The Governor General has expressed his condolences to the family, friends and colleagues of the miners.
Sir Anand Satyanand says it will be a disaster felt at many levels, from the immediate families, to the wider West Coast community.
Sir Anand also acknowledged those involved in the search and rescue operation, saying their commitment and dedication is much appreciated.
Mr Key says Cabinet will give the go-ahead on Monday for a commission of inquiry into the tragedy.
Energy Minister Gerry Brownlee says there will be many inquiries, some beginning immediately.
Mr Brownlee says he does not believe the mine was operating with excessive methane levels. He says the Department of Labour, which has responsibility for that aspect of mining operations, did not express concern about methane at the mine.
Labour Minister Kate Wilkinson says all aspects of safety at the Pike River Coal mine will be investigated.
Police Commissioner Howard Broad says no stone will be left unturned in examining what happened at the mine. Mr Broad says the decision of the officer in charge of the operation, Superintendent Gary Knowles, not to allow rescuers to go into the mine has been validated by the second explosion.
The chief coroner is also to open an inquiry into the disaster. At a coroner's conference in Auckland on Wednesday afternoon, Judge Neil McLean brought about 10 of the country's coroners together for an emergency briefing.
Gillard extends condolences
Australian Prime Minister Julia Gillard extended her nation's condolences to the miners' families.
Ms Gillard said 29 families have been hoping, praying and waiting to hear good news and now they have heard the most terrible news.
She said the hearts of all Australians went out to the miners.
Among the 29 miners were two Australians - Joshua Adam Ufer and William John Joynson.