New Zealand's government wants to ensure that the failure of the Christchurch City Council to properly process building permits does not delay the recovery of the city from devastating earthquakes.

The government will appoint its own manager after the council was stripped of its accreditation to issue consents, and other bodies are starting to take on some of Christchurch's work, Building and Construction Minister Maurice Williamson told Television New Zealand's Q+A on Saturday.

"We're farming that work out to a range of other councils so it doesn't delay things," Williamson said. "We hope that we can make sure it's as seamless as possible."

Christchurch faces a bill of 40 billion New Zealand dollars ($31 billion) to rebuild homes, commercial buildings, roads and pipelines after quakes that struck the nation's third-biggest city in 2010 and 2011.

Riskpool, the agency that provides the city with indemnity insurance, withdrew its backing on July 5, adding to concern that building and investment will grind to a halt. "It's a matter of restoring confidence really quickly," Williamson said.

It is unlikely any of the buildings approved under the flawed process are unsafe, because the failings were related to issues of documentation rather than structural integrity, he added.

He would not give an absolute commitment on that, nor estimate how many properties were affected.