Labour and Greens believe Christchurch City Council to be forced sell assets to pay for the CBD rebuild.
Labour's Christchurch East MP Lianne Dalziel says the council has held on to its revenue-generating assets for years to keep rates in check.
"To find out that the pressure is now on the city council to sell these assets to fund the government's plans is a step too far," she said on Wednesday.
The government on Monday unveiled the plan for the new CBD but designs aren't finalised and there's no costing for it.
Earthquake Recovery Minister Gerry Brownlee told reporters he was going to discuss funding with the council.
"We are not ruling anything in or anything out," he said.
"The council is in a difficult position, they've got a job on their hands that no other council in New Zealand has ever had to deal with - having discussions is very important and I'm not going to prejudice them beforehand."
The Greens questioned Mr Brownlee in parliament, but apart from confirming he had received advice from Treasury about selling assets to help pay for the rebuild he wouldn't reveal anything else.