Key has also revealed he was blindsided by Social Housing Minister Paula Bennett's announcement last week of a $5000 payment for homeless Aucklanders who relocate out of the city.
The Government has been criticised by opposition parties and social housing providers for a lack of housing initiatives in the Budget, with rising levels of homelessness and house price increases in Auckland.
Key said the Government was working on a number of "important initiatives" to address housing issues, and had allocated $200 million in the Budget for social housing with another $41m for emergency housing.
"There's plenty going on."
A national policy statement on urban development, to ensure councils freed up enough land for housing, would soon be released for consultation, while the Government had been "absolutely clear" to Auckland Council about the need to address the issue in its unitary plan.
However, Key said the Government would continue to monitor the situation in Auckland and elsewhere and determine whether it needed to do more.
"There's always a battle, if you like, for resources, and that includes the support that we give to the most vulnerable...we're always looking at different areas [of the sector].
"I don't think you can rationally say that we're not doing quite a lot, because we're doing a lot more than previous governments have done, but we'll keep monitoring that."
'I WASN'T AWARE IT WOULD BE THAT DAY'
Key also revealed he had been unaware of Bennett's plans to announce a $5000 grant for homeless people or those in state houses to move out of Auckland, and into areas with less demand on housing.
Bennett's announcement, the day before the Budget, also caught Finance Minister Bill English unawares when he was asked about it at the time by media.
Key said the Cabinet had discussed a potential expansion of a similar scheme earlier in the year, but he did not know Bennett would be announcing it when she did.
"I wasn't aware she was going to do it that day, but I was aware at some point she was likely to do that.
"It's a pretty small amount, it's potentially 1500 people and $750,000 so it's quite within her delegations."
However, Bennett said at the time of her announcement that the policy would cover up to 150 families, not 1500 people.