Housing Minister Nick Smith is warning a group of developers in Special Housing Areas to start building homes or risk losing their privileges.
Since 2013, 84 Special Housing Areas (SHAs) have been set up in Auckland to speed up the supply of new houses.
Mr Key told reporters at his post-Cabinet press conference this afternoon that most of the SHAs had indicated that they were starting work, but 14 of them had reported that they were not making progress.
"We haven't had any advice that they've started doing the preliminary work they need to," he said.
"They will probably find that in the next few days they will be getting a letter from Nick Smith saying that if they don't progress and bring those Special Housing Areas onto the market then the Special Housing Area designation will be taken off them."