Former minister Gerry Brownlee has denied leaving the new government to carry the can after revelations of a $200 million blowout for fixing botched earthquake repairs.

The minister responsible for the Earthquake Commission, Megan Woods, on Thursday announced the bill for "re-repairs" of earthquake damaged homes and cash settlements in Christchurch had hit $270m, compared to an official estimate of $70m just two years ago.

She's asked the Treasury to urgently look at how much more the government might be facing and has accused the previous government of "wilfully ignoring" the problem.

But her predecessor, Mr Brownlee, says he's not surprised by the figures, given more claims in total had come to light.

"If you look at the total cost of the EQC repair bill and then you look at what percentage that presents on a call-back basis, and then compare that to call- backs on a brand new build, it's still very low," he told Radio NZ on Friday.

"Estimates, in the end, are estimates."

The previous government had never looked to cap its spending on the repairs and many of the follow-up repairs were caused by hundreds of smaller quakes over the period, not just botched work, Mr Brownlee said.

"You can't walk away from that obligation. We never did," he said.

"The value of the EQC repair programme was there for someone to go to if you found you didn't have good work."

Dr Wood's allegations the previous government had walked away from Christchurch by scaling down EQC was "scurrilous" and "disgraceful", he said.

The figures come as the government shakes up the commission in a bid to clear out the last remaining 2600 claims from the deadly 2011 Christchurch quake.

Dame Annette King has been appointed interim chair - following the resignation of Sir Maarten Wevers - with an aim to speed up the resolution of outstanding claims.

- NZ Newswire