Prime Minister John Key says the estimated cost of rebuilding after the Canterbury earthquakes has risen to $40 billion.
The latest Treasury figures are $10 billion higher than its previous estimate.
Mr Key released the information during a National Party regional conference in Hanmer Springs on Sunday.
He said rebuilding Christchurch is the largest, most complex single economic project in New Zealand's history.
The prime minister said the $40 billion estimate will be included in the Budget on 16 May and will include capital costs incurred by the Government and private business.
Mr Key said the Budget will also show that the net fiscal cost of the earthquakes to the Crown has risen from December's estimate of $13 billion, to about $15 billion.
The estimates will continue to be updated, he said, and do not change the Government's commitment to Christchurch and Canterbury.
Canterbury Employers Chamber of Commerce last week put the cost of rebuilding Christchurch at $40 billion and accused the Government of dragging the chain on establishing an accurate total cost.