The cost of the Canterbury earthquake rebuild is now expected to hit $20 billion, $5 billion more than forecast in May's Budget.

Treasury is warning it may go up to $30 billion once costs such as damage to property and infrastructure are included.

The figure was revealed in today's pre-election fiscal update, which Treasury provides so all political parties can make an accurate estimate of the financial situation for the next three years.

The increased cost of the quake rebuild is being put down to higher than expected costs for repairing homes, higher estimates of damage from the February 22 quake and the inclusion of damage caused by the June 13th and other aftershocks.


It's expected reconstruction work won't properly start until mid way through next year, a six to nine month delay from that predicted in the Budget.