The government's National Housing and Planning Advice Unit (NHPAU) said last week that numbers of homes in England should be raised by more than a quarter of a million above the three million target by 2020.
But the East of England Regional Assembly voiced concerns about meeting this. Head of planning and housing Adrian Cannard said: "We would need to deliver 38,000 homes per year. The East of England plan suggests 27,000, which we feel is the most that can be achieved."
South East England Regional Assembly chairman Keith Mitchell argued: "Against a housing stock of 3.5 million in the South East, adding a few thousand every year will have almost no impact on prices. The affordability crisis needs a range of solutions."
He said the unit's figures ignore the costs of services and infrastructure for homes and "cut across the democratic process of agreeing regional housing figures".
However, NHPAU chief executive Kevin Williamson said there is no doubt that boosting housing numbers will affect affordability.
"We will work with development agencies, assemblies and government offices to look at delivery issues in the regions," he insisted.
Developing a Target Range for the Supply of New Homes across England is available at PlanningResource.co.uk/doc.