The Minister for Greater Christchurch Regeneration has ordered the Earthquake Commission to determine what the bill will be for damaged buildings which weren't repaired properly.

There are suggestions the Government could be left with as much as a billion dollar bill for re-repairing hundreds of earthquake damaged house in Christchurch.

Hundreds of people have unknowingly bought these damaged homes.

Megan Woods says they know of 664 cases where people unknowingly bought houses that were not properly repaired.

"In terms of how big the problem is, we simply don't know.

"That's why I've asked EQC to do the work quantifying it and it is frustrating that we know that the first level cases on this were filed back in May 2016."

She says it's yet to be determined who will foot the bill.

"We know that there's 664 of these cases at this stage.

"I've asked EQC to calculate what the potential liability for the Crown would be in re-repairing these houses if it were found that the Crown does have liability for them."