Planning chiefs have conceded they have not identified enough sites for housing in and around Norwich over the next five years.

And critics of a blueprint for where homes should be created over the next 25 years say that shows their plan for where more than 30,000 homes should be built by 2026 is flawed.

The blueprint – the Joint Core Strategy – has been drawn up by the Greater Norwich Development Partnership, made up of Norwich City Council, South Norfolk Council, Broadland District Council, Norfolk County Council and the Broads Authority.

Following a successful legal challenge by Salhouse campaigner Stephen Heard, part of the plan has had to go before a planning inspector once again. And at yesterday's planning inquiry, council officers found their calculations over new homes called into question.

Officers initially said they had identified enough sites to provide housing for 4.58 years – across Norwich, Broadland and South Norfolk combined.

But representatives for developers Landstock Estates gave the example of St Anne's Wharf in King Street, Norwich, as somewhere where the council figures did not stack up.

Andrew Willford, from planning consultants Barton Willmore, pointed out that, although the site had permission for 437 homes, the owners had gone into administration and the city council's cabinet recently heard it was more likely only about 90 homes would be built there.

Council officers said that, if only 90 homes were built, it would mean there were only enough homes earmarked to cover the next 4.48 years.

Planning inspector David Vickery will now consider what modifications should be made to the strategy, but he warned council officers they could have to face making a 'quick fix' to get homes built or could face 'planning by appeal' – with developers putting in speculative applications for sites, not necessarily in areas the blueprint had designated for development.