The estimated cost of rebuilding Christchurch has ballooned to $40 billion with Prime Minister John Key describing the project as the largest and most complex in New Zealand history.
The $40b estimate, which includes capital costs incurred by businesses and other entities, would be included in next month's Budget, Mr Key said.
Despite the $10b blowout from the $30b estimate in December's half-year fiscal update, the Government maintains it is on track to bring the Budget to surplus in 2014/15.
The estimated net fiscal cost of the earthquakes to the Government will rise from around $13b at the to around $15b.
Mr Key revealed the estimate increase at the National Party Mainland Region conference today, saying a lack of precise information previously was to blame for the blowout.
"This is the largest and most complex, single economic project in New Zealand's history. The scale of the rebuild is unprecedented," Mr Key said.
"That always meant that it would be difficult to get an exact handle on the total estimated cost straight away."
The prime minister reaffirmed his commitment to the rebuild.
"These estimates will continue to be updated from time to time, but they do not change the Government's commitment to Christchurch and Canterbury," he said.
"We will do what it takes to rebuild our second largest city, and that commitment will be unwavering."