The Christchurch earthquakes caused more than $NZ20 billion ($15.4 billion) damage, and business disruption, insurance and other costs will add another $NZ10 billion ($7.7 billion) according to the New Zealand Budget papers.

Finance Minister Bill English says rebuilding Christchurch will be a key driver of domestic activity and is expected to contribute about one percentage point to annual growth every calendar year to 2016.

Presenting the Budget in Wellington last week, he said the rebuilding process “is without doubt the largest and most complex economic project in New Zealand’s history”.

Supporting the rebuilding is one of the New Zealand Government’s four key priorities in 2012/13.

The Budget papers say recent aftershocks are likely to delay some rebuilding by three to six months.

“We continue to assume earthquake damage to property, contents and infrastructure of around $NZ20 billion in today’s prices, with only modest additional damage from the earthquakes since December 23,” Mr English said.

“Total costs, including business disruption or additional costs from inflation, insurance administration or rebuilding to higher standards than existed before the earthquakes, will be higher than this at around $30 billion ($23 billion).”

Nearly 5000 of the 7000 property owners in the residential red zone have accepted the Government’s offer to buy their properties. About half the offers have been settled.

The cost of buying red zone properties was $NZ1.04 billion ($800 million) in 2010/11, falling to $NZ454 million ($349 million) this year as the offer period ends.

Another $NZ13 million ($10 million) will be set aside for red zone expenses next year and $10 million will be allocated to demolish red zone properties.

The Government’s earthquake expenses will be $NZ900 million ($692 million) this year, $600 million ($461 million) in 2012/13 and $1.2 billion ($920 million) in 2013/14.