National housing spokesperson Amy Adams has faltered on a question about the number of houses built in Auckland, saying she could not give an exact number.

The AM Show invited Labour's housing spokesperson Phil Twyford and National's housing spokesperson Amy Adams to discuss what they plan to do about the housing shortage in Auckland, where the average house now costs $1 million.

When asked by host Duncan Garner if there was a housing crisis, Ms Adams said she would describe the situation as "housing pressures".

"For me this is a problem that is being solved. We can see right now very tangible signs. We've got 30,000 houses a year being built," she said.

"We're seeing house prices in Auckland flat to falling, so we're definitely seeing signs of the work that we've been doing over nine years."

National had aimed to build an average of 13,000 houses a year for three years to 2016 in Auckland. Garner asked Ms Adams how many had actually been built.

"No, I couldn't give you an exact number," she said - also unable to say how many affordable homes National had overseen in the last three years in Auckland.

"How can you be the housing spokesperson addressing a problem if you do not know the number of houses that were built in Auckland last year?" Garner asked.

Ms Adams said she had freed up planning rules, and blamed the councils for restricting land supply and failing to provide infrastructure.

"The obligation to provide enough land for housing, the obligation to put in place the infrastructure that's needed for housing sits with the council," she said

"What we've seen over many years and many parts of the country is the councils haven't done enough of that.

"So we've now changed the planning rules - which Labour opposed, we've put in place an NPS [National Policy Statement] on urban development - which Labour opposed, we've put in place special housing areas - which Labour opposed, and we're now funding $1.6 billion in infrastructure to help councils do what they haven't done enough of. And it's working."

Mr Twyford agreed with Garner that the correct number of houses built was 6,800 - "and that is about half what Auckland needs just to keep up with population demand".

"It's coming on top of the fact that 40,000 homes - Auckland's short that number, 40,000 that has built up on National's watch," he said.

"It's made life so much harder than it needed to be for so many people.

"They do blame this Government for not doing anything serious for the last nine years about this problem. It's their legacy, it's their biggest failure."

Mr Twyford said he would use "the power of government" to build a 100,000 affordable homes.

"We will take stock of every single development in Auckland that is currently being planned and underway to increase the share of affordable and state housing," he said.

Newshub.